Synopsys DesignWare Core SuperSpeed USB 3.0 Controller¶

Author: Felipe Balbi <felipe.balbi@linux.intel.com>
Date: April 2017

Introduction¶

The Synopsys DesignWare Core SuperSpeed USB 3.0 Controller (hereinafter referred to as DWC3) is a USB SuperSpeed compliant controller which can be configured in one of 4 ways:

Peripheral-only configuration

Host-only configuration

Dual-Role configuration

Hub configuration

Linux currently supports several versions of this controller. In all likelyhood, the version in your SoC is already supported. At the time of this writing, known tested versions range from 2.02a to 3.10a. As a rule of thumb, anything above 2.02a should work reliably well.

Currently, we have many known users for this driver. In alphabetical order:

Cavium

Intel Corporation

Qualcomm

Rockchip

ST

Samsung

Texas Instruments

Xilinx

Summary of Features¶

For details about features supported by your version of DWC3, consult your IP team and/or Synopsys DesignWare Core SuperSpeed USB 3.0 Controller Databook. Following is a list of features supported by the driver at the time of this writing:

Up to 16 bidirectional endpoints (including the control pipe - ep0)

Flexible endpoint configuration

Simultaneous IN and OUT transfer support

Scatter-list support

Up to 256 TRBs 1 per endpoint

Support for all transfer types (Control, Bulk, Interrupt, and Isochronous)

SuperSpeed Bulk Streams

Link Power Management

Trace Events for debugging

DebugFS 3 interface

These features have all been exercised with many of the in-tree gadget drivers. We have verified both ConfigFS 4 and legacy gadget drivers.

Driver Design¶

The DWC3 driver sits on the drivers/usb/dwc3/ directory. All files related to this driver are in this one directory. This makes it easy for new-comers to read the code and understand how it behaves.

Because of DWC3’s configuration flexibility, the driver is a little complex in some places but it should be rather straightforward to understand.

The biggest part of the driver refers to the Gadget API.

Known Limitations¶

Like any other HW, DWC3 has its own set of limitations. To avoid constant questions about such problems, we decided to document them here and have a single location to where we could point users.

OUT Transfer Size Requirements¶

According to Synopsys Databook, all OUT transfer TRBs 1 must have their size field set to a value which is integer divisible by the endpoint’s wMaxPacketSize. This means that e.g. in order to receive a Mass Storage CBW 5, req->length must either be set to a value that’s divisible by wMaxPacketSize (1024 on SuperSpeed, 512 on HighSpeed, etc), or DWC3 driver must add a Chained TRB pointing to a throw-away buffer for the remaining length. Without this, OUT transfers will NOT start.

Note that as of this writing, this won’t be a problem because DWC3 is fully capable of appending a chained TRB for the remaining length and completely hide this detail from the gadget driver. It’s still worth mentioning because this seems to be the largest source of queries about DWC3 and non-working transfers.

TRB Ring Size Limitation¶

We, currently, have a hard limit of 256 TRBs 1 per endpoint, with the last TRB being a Link TRB 2 pointing back to the first. This limit is arbitrary but it has the benefit of adding up to exactly 4096 bytes, or 1 Page.

DWC3 driver will try its best to cope with more than 255 requests and, for the most part, it should work normally. However this is not something that has been exercised very frequently. If you experience any problems, see section Reporting Bugs below.

Reporting Bugs¶

Whenever you encounter a problem with DWC3, first and foremost you should make sure that:

You’re running latest tag from Linus’ tree

You can reproduce the error without any out-of-tree changes to DWC3

You have checked that it’s not a fault on the host machine

After all these are verified, then here’s how to capture enough information so we can be of any help to you.

Required Information¶

DWC3 relies exclusively on Trace Events for debugging. Everything is exposed there, with some extra bits being exposed to DebugFS 3.

In order to capture DWC3’s Trace Events you should run the following commands before plugging the USB cable to a host machine:

# mkdir -p /d
# mkdir -p /t
# mount -t debugfs none /d
# mount -t tracefs none /t
# echo 81920 > /t/buffer_size_kb
# echo 1 > /t/events/dwc3/enable

After this is done, you can connect your USB cable and reproduce the problem. As soon as the fault is reproduced, make a copy of files trace and regdump, like so:

# cp /t/trace /root/trace.txt
# cat /d/*dwc3*/regdump > /root/regdump.txt

Make sure to compress trace.txt and regdump.txt in a tarball and email it to me with linux-usb in Cc. If you want to be extra sure that I’ll help you, write your subject line in the following format:

[BUG REPORT] usb: dwc3: Bug while doing XYZ

On the email body, make sure to detail what you doing, which gadget driver you were using, how to reproduce the problem, what SoC you’re using, which OS (and its version) was running on the Host machine.

With all this information, we should be able to understand what’s going on and be helpful to you.

Debugging¶

First and foremost a disclaimer:

DISCLAIMER: The information available on DebugFS and/or TraceFS can
change at any time at any Major Linux Kernel Release. If writing
scripts, do **NOT** assume information to be available in the
current format.

With that out of the way, let’s carry on.

If you’re willing to debug your own problem, you deserve a round of applause :-)

Anyway, there isn’t much to say here other than Trace Events will be really helpful in figuring out issues with DWC3. Also, access to Synopsys Databook will be really valuable in this case.

A USB Sniffer can be helpful at times but it’s not entirely required, there’s a lot that can be understood without looking at the wire.

Feel free to email me and Cc linux-usb if you need any help.

`DebugFS`¶

DebugFS is very good for gathering snapshots of what’s going on with DWC3 and/or any endpoint.

On DWC3’s DebugFS directory, you will find the following files and directories:

ep[0..15]{in,out}/ link_state regdump testmode

`link_state`¶

When read, link_state will print out one of U0, U1, U2, U3, SS.Disabled, RX.Detect, SS.Inactive, Polling, Recovery, Hot Reset, Compliance, Loopback, Reset, Resume or UNKNOWN link state.

This file can also be written to in order to force link to one of the states above.

`regdump`¶

File name is self-explanatory. When read, regdump will print out a register dump of DWC3. Note that this file can be grepped to find the information you want.

`testmode`¶

When read, testmode will print out a name of one of the specified USB 2.0 Testmodes (test_j, test_k, test_se0_nak, test_packet, test_force_enable) or the string no test in case no tests are currently being executed.

In order to start any of these test modes, the same strings can be written to the file and DWC3 will enter the requested test mode.

`ep[0..15]{in,out}`¶

For each endpoint we expose one directory following the naming convention ep$num$dir (ep0in, ep0out, ep1in, …). Inside each of these directories you will find the following files:

descriptor_fetch_queue event_queue rx_fifo_queue rx_info_queue rx_request_queue transfer_type trb_ring tx_fifo_queue tx_request_queue

With access to Synopsys Databook, you can decode the information on them.

`transfer_type`¶

When read, transfer_type will print out one of control, bulk, interrupt or isochronous depending on what the endpoint descriptor says. If the endpoint hasn’t been enabled yet, it will print --.

`trb_ring`¶

When read, trb_ring will print out details about all TRBs on the ring. It will also tell you where our enqueue and dequeue pointers are located in the ring:

buffer_addr,size,type,ioc,isp_imi,csp,chn,lst,hwo
000000002c754000,481,normal,1,0,1,0,0,0
000000002c75c000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c78c000,481,normal,1,0,1,0,0,0
000000002c754000,481,normal,1,0,1,0,0,0
000000002c75c000,481,normal,1,0,1,0,0,0
000000002c784000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c78c000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c784000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c78c000,481,normal,1,0,1,0,0,0
000000002c754000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c784000,481,normal,1,0,1,0,0,0
000000002c78c000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c78c000,481,normal,1,0,1,0,0,0
000000002c784000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c78c000,481,normal,1,0,1,0,0,0
000000002c754000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c78c000,481,normal,1,0,1,0,0,0
000000002c75c000,481,normal,1,0,1,0,0,0
000000002c78c000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c754000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c754000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c78c000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c754000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c75c000,481,normal,1,0,1,0,0,0
000000002c780000,481,normal,1,0,1,0,0,0
000000002c784000,481,normal,1,0,1,0,0,0
000000002c788000,481,normal,1,0,1,0,0,0
000000002c78c000,481,normal,1,0,1,0,0,0
000000002c790000,481,normal,1,0,1,0,0,0
000000002c754000,481,normal,1,0,1,0,0,0
000000002c758000,481,normal,1,0,1,0,0,0
000000002c75c000,512,normal,1,0,1,0,0,1        D
0000000000000000,0,UNKNOWN,0,0,0,0,0,0       E
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
0000000000000000,0,UNKNOWN,0,0,0,0,0,0
00000000381ab000,0,link,0,0,0,0,0,1

Trace Events¶

DWC3 also provides several trace events which help us gathering information about the behavior of the driver during runtime.

In order to use these events, you must enable CONFIG_FTRACE in your kernel config.

For details about how enable DWC3 events, see section Reporting Bugs.

The following subsections will give details about each Event Class and each Event defined by DWC3.

MMIO¶

It is sometimes useful to look at every MMIO access when looking for bugs. Because of that, DWC3 offers two Trace Events (one for dwc3_readl() and one for dwc3_writel()). TP_printk follows:

TP_printk("addr %p value %08x", __entry->base + __entry->offset,
              __entry->value)

Interrupt Events¶

Every IRQ event can be logged and decoded into a human readable string. Because every event will be different, we don’t give an example other than the TP_printk format used:

TP_printk("event (%08x): %s", __entry->event,
              dwc3_decode_event(__entry->event, __entry->ep0state))

Control Request¶

Every USB Control Request can be logged to the trace buffer. The output format is:

TP_printk("%s", dwc3_decode_ctrl(__entry->bRequestType,
                              __entry->bRequest, __entry->wValue,
                              __entry->wIndex, __entry->wLength)
)

Note that Standard Control Requests will be decoded into human-readable strings with their respective arguments. Class and Vendor requests will be printed out a sequence of 8 bytes in hex format.

Lifetime of a `struct usb_request`¶

The entire lifetime of a struct usb_request can be tracked on the trace buffer. We have one event for each of allocation, free, queueing, dequeueing, and giveback. Output format is:

TP_printk("%s: req %p length %u/%u %s%s%s ==> %d",
      __get_str(name), __entry->req, __entry->actual, __entry->length,
      __entry->zero ? "Z" : "z",
      __entry->short_not_ok ? "S" : "s",
      __entry->no_interrupt ? "i" : "I",
      __entry->status
)

Generic Commands¶

We can log and decode every Generic Command with its completion code. Format is:

TP_printk("cmd '%s' [%x] param %08x --> status: %s",
      dwc3_gadget_generic_cmd_string(__entry->cmd),
      __entry->cmd, __entry->param,
      dwc3_gadget_generic_cmd_status_string(__entry->status)
)

Endpoint Commands¶

Endpoints commands can also be logged together with completion code. Format is:

TP_printk("%s: cmd '%s' [%d] params %08x %08x %08x --> status: %s",
      __get_str(name), dwc3_gadget_ep_cmd_string(__entry->cmd),
      __entry->cmd, __entry->param0,
      __entry->param1, __entry->param2,
      dwc3_ep_cmd_status_string(__entry->cmd_status)
)

Lifetime of a `TRB`¶

A TRB Lifetime is simple. We are either preparing a TRB or completing it. With these two events, we can see how a TRB changes over time. Format is:

TP_printk("%s: %d/%d trb %p buf %08x%08x size %s%d ctrl %08x (%c%c%c%c:%c%c:%s)",
      __get_str(name), __entry->queued, __entry->allocated,
      __entry->trb, __entry->bph, __entry->bpl,
      ({char *s;
      int pcm = ((__entry->size >> 24) & 3) + 1;
      switch (__entry->type) {
      case USB_ENDPOINT_XFER_INT:
      case USB_ENDPOINT_XFER_ISOC:
              switch (pcm) {
              case 1:
                      s = "1x ";
                      break;
              case 2:
                      s = "2x ";
                      break;
              case 3:
                      s = "3x ";
                      break;
              }
      default:
              s = "";
      } s; }),
      DWC3_TRB_SIZE_LENGTH(__entry->size), __entry->ctrl,
      __entry->ctrl & DWC3_TRB_CTRL_HWO ? 'H' : 'h',
      __entry->ctrl & DWC3_TRB_CTRL_LST ? 'L' : 'l',
      __entry->ctrl & DWC3_TRB_CTRL_CHN ? 'C' : 'c',
      __entry->ctrl & DWC3_TRB_CTRL_CSP ? 'S' : 's',
      __entry->ctrl & DWC3_TRB_CTRL_ISP_IMI ? 'S' : 's',
      __entry->ctrl & DWC3_TRB_CTRL_IOC ? 'C' : 'c',
    dwc3_trb_type_string(DWC3_TRBCTL_TYPE(__entry->ctrl))
)

Lifetime of an Endpoint¶

And endpoint’s lifetime is summarized with enable and disable operations, both of which can be traced. Format is:

TP_printk("%s: mps %d/%d streams %d burst %d ring %d/%d flags %c:%c%c%c%c%c:%c:%c",
      __get_str(name), __entry->maxpacket,
      __entry->maxpacket_limit, __entry->max_streams,
      __entry->maxburst, __entry->trb_enqueue,
      __entry->trb_dequeue,
      __entry->flags & DWC3_EP_ENABLED ? 'E' : 'e',
      __entry->flags & DWC3_EP_STALL ? 'S' : 's',
      __entry->flags & DWC3_EP_WEDGE ? 'W' : 'w',
      __entry->flags & DWC3_EP_TRANSFER_STARTED ? 'B' : 'b',
      __entry->flags & DWC3_EP_PENDING_REQUEST ? 'P' : 'p',
      __entry->flags & DWC3_EP_END_TRANSFER_PENDING ? 'E' : 'e',
      __entry->direction ? '<' : '>'
)

Structures, Methods and Definitions¶

struct dwc3_event_buffer¶: Software event buffer representation

Definition

struct dwc3_event_buffer {
  void *buf;
  void *cache;
  unsigned int            length;
  unsigned int            lpos;
  unsigned int            count;
  unsigned int            flags;
#define DWC3_EVENT_PENDING      BIT(0);
  dma_addr_t dma;
  struct dwc3             *dwc;
};

Members

buf: _THE_ buffer
cache: The buffer cache used in the threaded interrupt
length: size of this buffer
lpos: event offset
count: cache of last read event count register
flags: flags related to this event buffer
dma: dma_addr_t
dwc: pointer to DWC controller

struct dwc3_ep¶: device side endpoint representation

Definition

struct dwc3_ep {
  struct usb_ep           endpoint;
  struct list_head        cancelled_list;
  struct list_head        pending_list;
  struct list_head        started_list;
  void __iomem            *regs;
  struct dwc3_trb         *trb_pool;
  dma_addr_t trb_pool_dma;
  struct dwc3             *dwc;
  u32 saved_state;
  unsigned int            flags;
#define DWC3_EP_ENABLED                 BIT(0);
#define DWC3_EP_STALL                   BIT(1);
#define DWC3_EP_WEDGE                   BIT(2);
#define DWC3_EP_TRANSFER_STARTED        BIT(3);
#define DWC3_EP_END_TRANSFER_PENDING    BIT(4);
#define DWC3_EP_PENDING_REQUEST         BIT(5);
#define DWC3_EP_DELAY_START             BIT(6);
#define DWC3_EP_WAIT_TRANSFER_COMPLETE  BIT(7);
#define DWC3_EP_IGNORE_NEXT_NOSTREAM    BIT(8);
#define DWC3_EP_FORCE_RESTART_STREAM    BIT(9);
#define DWC3_EP_FIRST_STREAM_PRIMED     BIT(10);
#define DWC3_EP_PENDING_CLEAR_STALL     BIT(11);
#define DWC3_EP_TXFIFO_RESIZED          BIT(12);
#define DWC3_EP0_DIR_IN                 BIT(31);
  u8 trb_enqueue;
  u8 trb_dequeue;
  u8 number;
  u8 type;
  u8 resource_index;
  u32 frame_number;
  u32 interval;
  char name[20];
  unsigned direction:1;
  unsigned stream_capable:1;
  u8 combo_num;
  int start_cmd_status;
};

Members

endpoint: usb endpoint
cancelled_list: list of cancelled requests for this endpoint
pending_list: list of pending requests for this endpoint
started_list: list of started requests on this endpoint
regs: pointer to first endpoint register
trb_pool: array of transaction buffers
trb_pool_dma: dma address of trb_pool
dwc: pointer to DWC controller
saved_state: ep state saved during hibernation
flags: endpoint flags (wedged, stalled, …)
trb_enqueue: enqueue ‘pointer’ into TRB array
trb_dequeue: dequeue ‘pointer’ into TRB array
number: endpoint number (1 - 15)
type: set to bmAttributes & USB_ENDPOINT_XFERTYPE_MASK
resource_index: Resource transfer index
frame_number: set to the frame number we want this transfer to start (ISOC)
interval: the interval on which the ISOC transfer is started
name: a human readable name e.g. ep1out-bulk
direction: true for TX, false for RX
stream_capable: true when streams are enabled
combo_num: the test combination BIT[15:14] of the frame number to test isochronous START TRANSFER command failure workaround
start_cmd_status: the status of testing START TRANSFER command with combo_num = ‘b00

struct dwc3_trb¶: transfer request block (hw format)

Definition

struct dwc3_trb {
  u32 bpl;
  u32 bph;
  u32 size;
  u32 ctrl;
};

Members

bpl: DW0-3
bph: DW4-7
size: DW8-B
ctrl: DWC-F

struct dwc3_hwparams¶: copy of HWPARAMS registers

Definition

struct dwc3_hwparams {
  u32 hwparams0;
  u32 hwparams1;
  u32 hwparams2;
  u32 hwparams3;
  u32 hwparams4;
  u32 hwparams5;
  u32 hwparams6;
  u32 hwparams7;
  u32 hwparams8;
  u32 hwparams9;
};

Members

hwparams0: GHWPARAMS0
hwparams1: GHWPARAMS1
hwparams2: GHWPARAMS2
hwparams3: GHWPARAMS3
hwparams4: GHWPARAMS4
hwparams5: GHWPARAMS5
hwparams6: GHWPARAMS6
hwparams7: GHWPARAMS7
hwparams8: GHWPARAMS8
hwparams9: GHWPARAMS9

struct dwc3_request¶: representation of a transfer request

Definition

struct dwc3_request {
  struct usb_request      request;
  struct list_head        list;
  struct dwc3_ep          *dep;
  struct scatterlist      *sg;
  struct scatterlist      *start_sg;
  unsigned int            num_pending_sgs;
  unsigned int            num_queued_sgs;
  unsigned int            remaining;
  unsigned int            status;
#define DWC3_REQUEST_STATUS_QUEUED              0;
#define DWC3_REQUEST_STATUS_STARTED             1;
#define DWC3_REQUEST_STATUS_DISCONNECTED        2;
#define DWC3_REQUEST_STATUS_DEQUEUED            3;
#define DWC3_REQUEST_STATUS_STALLED             4;
#define DWC3_REQUEST_STATUS_COMPLETED           5;
#define DWC3_REQUEST_STATUS_UNKNOWN             -1;
  u8 epnum;
  struct dwc3_trb         *trb;
  dma_addr_t trb_dma;
  unsigned int            num_trbs;
  unsigned int            needs_extra_trb:1;
  unsigned int            direction:1;
  unsigned int            mapped:1;
};

Members

request: struct usb_request to be transferred
list: a list_head used for request queueing
dep: struct dwc3_ep owning this request
sg: pointer to first incomplete sg
start_sg: pointer to the sg which should be queued next
num_pending_sgs: counter to pending sgs
num_queued_sgs: counter to the number of sgs which already got queued
remaining: amount of data remaining
status: internal dwc3 request status tracking
epnum: endpoint number to which this request refers
trb: pointer to struct dwc3_trb
trb_dma: DMA address of trb
num_trbs: number of TRBs used by this request
needs_extra_trb: true when request needs one extra TRB (either due to ZLP or unaligned OUT)
direction: IN or OUT direction flag
mapped: true when request has been dma-mapped

struct dwc3¶: representation of our controller

Definition

struct dwc3 {
  struct work_struct      drd_work;
  struct dwc3_trb         *ep0_trb;
  void *bounce;
  void *scratchbuf;
  u8 *setup_buf;
  dma_addr_t ep0_trb_addr;
  dma_addr_t bounce_addr;
  dma_addr_t scratch_addr;
  struct dwc3_request     ep0_usb_req;
  struct completion       ep0_in_setup;
  spinlock_t lock;
  struct mutex            mutex;
  struct device           *dev;
  struct device           *sysdev;
  struct platform_device  *xhci;
  struct resource         xhci_resources[DWC3_XHCI_RESOURCES_NUM];
  struct dwc3_event_buffer *ev_buf;
  struct dwc3_ep          *eps[DWC3_ENDPOINTS_NUM];
  struct usb_gadget       *gadget;
  struct usb_gadget_driver *gadget_driver;
  struct clk_bulk_data    *clks;
  int num_clks;
  struct reset_control    *reset;
  struct usb_phy          *usb2_phy;
  struct usb_phy          *usb3_phy;
  struct phy              *usb2_generic_phy;
  struct phy              *usb3_generic_phy;
  bool phys_ready;
  struct ulpi             *ulpi;
  bool ulpi_ready;
  void __iomem            *regs;
  size_t regs_size;
  enum usb_dr_mode        dr_mode;
  u32 current_dr_role;
  u32 desired_dr_role;
  struct extcon_dev       *edev;
  struct notifier_block   edev_nb;
  enum usb_phy_interface  hsphy_mode;
  struct usb_role_switch  *role_sw;
  enum usb_dr_mode        role_switch_default_mode;
  struct power_supply     *usb_psy;
  u32 fladj;
  u32 ref_clk_per;
  u32 irq_gadget;
  u32 otg_irq;
  u32 current_otg_role;
  u32 desired_otg_role;
  bool otg_restart_host;
  u32 nr_scratch;
  u32 u1u2;
  u32 maximum_speed;
  u32 gadget_max_speed;
  enum usb_ssp_rate       max_ssp_rate;
  enum usb_ssp_rate       gadget_ssp_rate;
  u32 ip;
#define DWC3_IP                 0x5533;
#define DWC31_IP                0x3331;
#define DWC32_IP                0x3332;
  u32 revision;
#define DWC3_REVISION_ANY       0x0;
#define DWC3_REVISION_173A      0x5533173a;
#define DWC3_REVISION_175A      0x5533175a;
#define DWC3_REVISION_180A      0x5533180a;
#define DWC3_REVISION_183A      0x5533183a;
#define DWC3_REVISION_185A      0x5533185a;
#define DWC3_REVISION_187A      0x5533187a;
#define DWC3_REVISION_188A      0x5533188a;
#define DWC3_REVISION_190A      0x5533190a;
#define DWC3_REVISION_194A      0x5533194a;
#define DWC3_REVISION_200A      0x5533200a;
#define DWC3_REVISION_202A      0x5533202a;
#define DWC3_REVISION_210A      0x5533210a;
#define DWC3_REVISION_220A      0x5533220a;
#define DWC3_REVISION_230A      0x5533230a;
#define DWC3_REVISION_240A      0x5533240a;
#define DWC3_REVISION_250A      0x5533250a;
#define DWC3_REVISION_260A      0x5533260a;
#define DWC3_REVISION_270A      0x5533270a;
#define DWC3_REVISION_280A      0x5533280a;
#define DWC3_REVISION_290A      0x5533290a;
#define DWC3_REVISION_300A      0x5533300a;
#define DWC3_REVISION_310A      0x5533310a;
#define DWC3_REVISION_330A      0x5533330a;
#define DWC31_REVISION_ANY      0x0;
#define DWC31_REVISION_110A     0x3131302a;
#define DWC31_REVISION_120A     0x3132302a;
#define DWC31_REVISION_160A     0x3136302a;
#define DWC31_REVISION_170A     0x3137302a;
#define DWC31_REVISION_180A     0x3138302a;
#define DWC31_REVISION_190A     0x3139302a;
#define DWC32_REVISION_ANY      0x0;
#define DWC32_REVISION_100A     0x3130302a;
  u32 version_type;
#define DWC31_VERSIONTYPE_ANY           0x0;
#define DWC31_VERSIONTYPE_EA01          0x65613031;
#define DWC31_VERSIONTYPE_EA02          0x65613032;
#define DWC31_VERSIONTYPE_EA03          0x65613033;
#define DWC31_VERSIONTYPE_EA04          0x65613034;
#define DWC31_VERSIONTYPE_EA05          0x65613035;
#define DWC31_VERSIONTYPE_EA06          0x65613036;
  enum dwc3_ep0_next      ep0_next_event;
  enum dwc3_ep0_state     ep0state;
  enum dwc3_link_state    link_state;
  u16 u2sel;
  u16 u2pel;
  u8 u1sel;
  u8 u1pel;
  u8 speed;
  u8 num_eps;
  struct dwc3_hwparams    hwparams;
  struct debugfs_regset32 *regset;
  u32 dbg_lsp_select;
  u8 test_mode;
  u8 test_mode_nr;
  u8 lpm_nyet_threshold;
  u8 hird_threshold;
  u8 rx_thr_num_pkt_prd;
  u8 rx_max_burst_prd;
  u8 tx_thr_num_pkt_prd;
  u8 tx_max_burst_prd;
  u8 tx_fifo_resize_max_num;
  const char              *hsphy_interface;
  unsigned connected:1;
  unsigned softconnect:1;
  unsigned delayed_status:1;
  unsigned ep0_bounced:1;
  unsigned ep0_expect_in:1;
  unsigned has_hibernation:1;
  unsigned sysdev_is_parent:1;
  unsigned has_lpm_erratum:1;
  unsigned is_utmi_l1_suspend:1;
  unsigned is_fpga:1;
  unsigned pending_events:1;
  unsigned do_fifo_resize:1;
  unsigned pullups_connected:1;
  unsigned setup_packet_pending:1;
  unsigned three_stage_setup:1;
  unsigned dis_start_transfer_quirk:1;
  unsigned usb3_lpm_capable:1;
  unsigned usb2_lpm_disable:1;
  unsigned usb2_gadget_lpm_disable:1;
  unsigned disable_scramble_quirk:1;
  unsigned u2exit_lfps_quirk:1;
  unsigned u2ss_inp3_quirk:1;
  unsigned req_p1p2p3_quirk:1;
  unsigned del_p1p2p3_quirk:1;
  unsigned del_phy_power_chg_quirk:1;
  unsigned lfps_filter_quirk:1;
  unsigned rx_detect_poll_quirk:1;
  unsigned dis_u3_susphy_quirk:1;
  unsigned dis_u2_susphy_quirk:1;
  unsigned dis_enblslpm_quirk:1;
  unsigned dis_u1_entry_quirk:1;
  unsigned dis_u2_entry_quirk:1;
  unsigned dis_rxdet_inp3_quirk:1;
  unsigned dis_u2_freeclk_exists_quirk:1;
  unsigned dis_del_phy_power_chg_quirk:1;
  unsigned dis_tx_ipgap_linecheck_quirk:1;
  unsigned parkmode_disable_ss_quirk:1;
  unsigned tx_de_emphasis_quirk:1;
  unsigned tx_de_emphasis:2;
  unsigned dis_metastability_quirk:1;
  unsigned dis_split_quirk:1;
  unsigned async_callbacks:1;
  u16 imod_interval;
  int max_cfg_eps;
  int last_fifo_depth;
  int num_ep_resized;
};

Members

drd_work: workqueue used for role swapping
ep0_trb: trb which is used for the ctrl_req
bounce: address of bounce buffer
scratchbuf: address of scratch buffer
setup_buf: used while precessing STD USB requests
ep0_trb_addr: dma address of ep0_trb
bounce_addr: dma address of bounce
scratch_addr: dma address of scratchbuf
ep0_usb_req: dummy req used while handling STD USB requests
ep0_in_setup: one control transfer is completed and enter setup phase
lock: for synchronizing
mutex: for mode switching
dev: pointer to our struct device
sysdev: pointer to the DMA-capable device
xhci: pointer to our xHCI child
xhci_resources: struct resources for our xhci child
ev_buf: struct dwc3_event_buffer pointer
eps: endpoint array
gadget: device side representation of the peripheral controller
gadget_driver: pointer to the gadget driver
clks: array of clocks
num_clks: number of clocks
reset: reset control
usb2_phy: pointer to USB2 PHY
usb3_phy: pointer to USB3 PHY
usb2_generic_phy: pointer to USB2 PHY
usb3_generic_phy: pointer to USB3 PHY
phys_ready: flag to indicate that PHYs are ready
ulpi: pointer to ulpi interface
ulpi_ready: flag to indicate that ULPI is initialized
regs: base address for our registers
regs_size: address space size
dr_mode: requested mode of operation
current_dr_role: current role of operation when in dual-role mode
desired_dr_role: desired role of operation when in dual-role mode
edev: extcon handle
edev_nb: extcon notifier
hsphy_mode: UTMI phy mode, one of following: - USBPHY_INTERFACE_MODE_UTMI - USBPHY_INTERFACE_MODE_UTMIW
role_sw: usb_role_switch handle
role_switch_default_mode: default operation mode of controller while usb role is USB_ROLE_NONE.
usb_psy: pointer to power supply interface.
fladj: frame length adjustment
ref_clk_per: reference clock period configuration
irq_gadget: peripheral controller’s IRQ number
otg_irq: IRQ number for OTG IRQs
current_otg_role: current role of operation while using the OTG block
desired_otg_role: desired role of operation while using the OTG block
otg_restart_host: flag that OTG controller needs to restart host
nr_scratch: number of scratch buffers
u1u2: only used on revisions <1.83a for workaround
maximum_speed: maximum speed requested (mainly for testing purposes)
gadget_max_speed: maximum gadget speed requested
max_ssp_rate: SuperSpeed Plus maximum signaling rate and lane count
gadget_ssp_rate: Gadget driver’s maximum supported SuperSpeed Plus signaling rate and lane count.
ip: controller’s ID
revision: controller’s version of an IP
version_type: VERSIONTYPE register contents, a sub release of a revision
ep0_next_event: hold the next expected event
ep0state: state of endpoint zero
link_state: link state
u2sel: parameter from Set SEL request.
u2pel: parameter from Set SEL request.
u1sel: parameter from Set SEL request.
u1pel: parameter from Set SEL request.
speed: device speed (super, high, full, low)
num_eps: number of endpoints
hwparams: copy of hwparams registers
regset: debugfs pointer to regdump file
dbg_lsp_select: current debug lsp mux register selection
test_mode: true when we’re entering a USB test mode
test_mode_nr: test feature selector
lpm_nyet_threshold: LPM NYET response threshold
hird_threshold: HIRD threshold
rx_thr_num_pkt_prd: periodic ESS receive packet count
rx_max_burst_prd: max periodic ESS receive burst size
tx_thr_num_pkt_prd: periodic ESS transmit packet count
tx_max_burst_prd: max periodic ESS transmit burst size
tx_fifo_resize_max_num: max number of fifos allocated during txfifo resize
hsphy_interface: “utmi” or “ulpi”
connected: true when we’re connected to a host, false otherwise
softconnect: true when gadget connect is called, false when disconnect runs
delayed_status: true when gadget driver asks for delayed status
ep0_bounced: true when we used bounce buffer
ep0_expect_in: true when we expect a DATA IN transfer
has_hibernation: true when dwc3 was configured with Hibernation
sysdev_is_parent: true when dwc3 device has a parent driver
has_lpm_erratum: true when core was configured with LPM Erratum. Note that there’s now way for software to detect this in runtime.
is_utmi_l1_suspend: the core asserts output signal 0 - utmi_sleep_n 1 - utmi_l1_suspend_n
is_fpga: true when we are using the FPGA board
pending_events: true when we have pending IRQs to be handled
do_fifo_resize: true when txfifo resizing is enabled for dwc3 endpoints
pullups_connected: true when Run/Stop bit is set
setup_packet_pending: true when there’s a Setup Packet in FIFO. Workaround
three_stage_setup: set if we perform a three phase setup
dis_start_transfer_quirk: set if start_transfer failure SW workaround is not needed for DWC_usb31 version 1.70a-ea06 and below
usb3_lpm_capable: set if hadrware supports Link Power Management
usb2_lpm_disable: set to disable usb2 lpm for host
usb2_gadget_lpm_disable: set to disable usb2 lpm for gadget
disable_scramble_quirk: set if we enable the disable scramble quirk
u2exit_lfps_quirk: set if we enable u2exit lfps quirk
u2ss_inp3_quirk: set if we enable P3 OK for U2/SS Inactive quirk
req_p1p2p3_quirk: set if we enable request p1p2p3 quirk
del_p1p2p3_quirk: set if we enable delay p1p2p3 quirk
del_phy_power_chg_quirk: set if we enable delay phy power change quirk
lfps_filter_quirk: set if we enable LFPS filter quirk
rx_detect_poll_quirk: set if we enable rx_detect to polling lfps quirk
dis_u3_susphy_quirk: set if we disable usb3 suspend phy
dis_u2_susphy_quirk: set if we disable usb2 suspend phy
dis_enblslpm_quirk: set if we clear enblslpm in GUSB2PHYCFG, disabling the suspend signal to the PHY.
dis_u1_entry_quirk: set if link entering into U1 state needs to be disabled.
dis_u2_entry_quirk: set if link entering into U2 state needs to be disabled.
dis_rxdet_inp3_quirk: set if we disable Rx.Detect in P3
dis_u2_freeclk_exists_quirk: set if we clear u2_freeclk_exists in GUSB2PHYCFG, specify that USB2 PHY doesn’t provide a free-running PHY clock.
dis_del_phy_power_chg_quirk: set if we disable delay phy power change quirk.
dis_tx_ipgap_linecheck_quirk: set if we disable u2mac linestate check during HS transmit.
parkmode_disable_ss_quirk: set if we need to disable all SuperSpeed instances in park mode.
tx_de_emphasis_quirk: set if we enable Tx de-emphasis quirk
tx_de_emphasis: Tx de-emphasis value 0 - -6dB de-emphasis 1 - -3.5dB de-emphasis 2 - No de-emphasis 3 - Reserved
dis_metastability_quirk: set to disable metastability quirk.
dis_split_quirk: set to disable split boundary.
imod_interval: set the interrupt moderation interval in 250ns increments or 0 to disable.
max_cfg_eps: current max number of IN eps used across all USB configs.
last_fifo_depth: last fifo depth used to determine next fifo ram start address.
num_ep_resized: carries the current number endpoints which have had its tx fifo resized.

struct dwc3_event_depevt¶: Device Endpoint Events

Definition

struct dwc3_event_depevt {
  u32 one_bit:1;
  u32 endpoint_number:5;
  u32 endpoint_event:4;
  u32 reserved11_10:2;
  u32 status:4;
#define DEPEVT_STATUS_TRANSFER_ACTIVE   BIT(3);
#define DEPEVT_STATUS_BUSERR    BIT(0);
#define DEPEVT_STATUS_SHORT     BIT(1);
#define DEPEVT_STATUS_IOC       BIT(2);
#define DEPEVT_STATUS_LST       BIT(3) ;
#define DEPEVT_STATUS_MISSED_ISOC BIT(3) ;
#define DEPEVT_STREAMEVT_FOUND          1;
#define DEPEVT_STREAMEVT_NOTFOUND       2;
#define DEPEVT_STREAM_PRIME             0xfffe;
#define DEPEVT_STREAM_NOSTREAM          0x0;
#define DEPEVT_STATUS_CONTROL_DATA      1;
#define DEPEVT_STATUS_CONTROL_STATUS    2;
#define DEPEVT_STATUS_CONTROL_PHASE(n)  ((n) & 3);
#define DEPEVT_TRANSFER_NO_RESOURCE     1;
#define DEPEVT_TRANSFER_BUS_EXPIRY      2;
  u32 parameters:16;
#define DEPEVT_PARAMETER_CMD(n) (((n) & (0xf << 8)) >> 8);
};

Members

one_bit: indicates this is an endpoint event (not used)
endpoint_number: number of the endpoint
endpoint_event: The event we have: 0x00 - Reserved 0x01 - XferComplete 0x02 - XferInProgress 0x03 - XferNotReady 0x04 - RxTxFifoEvt (IN->Underrun, OUT->Overrun) 0x05 - Reserved 0x06 - StreamEvt 0x07 - EPCmdCmplt
reserved11_10: Reserved, don’t use.
status: Indicates the status of the event. Refer to databook for more information.
parameters: Parameters of the current event. Refer to databook for more information.

struct dwc3_event_devt¶: Device Events

Definition

struct dwc3_event_devt {
  u32 one_bit:1;
  u32 device_event:7;
  u32 type:4;
  u32 reserved15_12:4;
  u32 event_info:9;
  u32 reserved31_25:7;
};

Members

one_bit: indicates this is a non-endpoint event (not used)
device_event: indicates it’s a device event. Should read as 0x00
type: indicates the type of device event. 0 - DisconnEvt 1 - USBRst 2 - ConnectDone 3 - ULStChng 4 - WkUpEvt 5 - Reserved 6 - Suspend (EOPF on revisions 2.10a and prior) 7 - SOF 8 - Reserved 9 - ErrticErr 10 - CmdCmplt 11 - EvntOverflow 12 - VndrDevTstRcved
reserved15_12: Reserved, not used
event_info: Information about this event
reserved31_25: Reserved, not used

struct dwc3_event_gevt¶: Other Core Events

Definition

struct dwc3_event_gevt {
  u32 one_bit:1;
  u32 device_event:7;
  u32 phy_port_number:4;
  u32 reserved31_12:20;
};

Members

one_bit: indicates this is a non-endpoint event (not used)
device_event: indicates it’s (0x03) Carkit or (0x04) I2C event.
phy_port_number: self-explanatory
reserved31_12: Reserved, not used.

union dwc3_event¶: representation of Event Buffer contents

Definition

union dwc3_event {
  u32 raw;
  struct dwc3_event_type          type;
  struct dwc3_event_depevt        depevt;
  struct dwc3_event_devt          devt;
  struct dwc3_event_gevt          gevt;
};

Members

raw: raw 32-bit event
type: the type of the event
depevt: Device Endpoint Event
devt: Device Event
gevt: Global Event

struct dwc3_gadget_ep_cmd_params¶: representation of endpoint command parameters

Definition

struct dwc3_gadget_ep_cmd_params {
  u32 param2;
  u32 param1;
  u32 param0;
};

Members

param2: third parameter
param1: second parameter
param0: first parameter

u32 dwc3_mdwidth(struct dwc3 *dwc)¶: get MDWIDTH value in bits

Parameters

struct dwc3 *dwc: pointer to our context structure

Description

Return MDWIDTH configuration value in bits.

struct dwc3_request *next_request(struct list_head *list)¶: gets the next request on the given list

Parameters

struct list_head *list: the request list to operate on

Description

Caller should take care of locking. This function return NULL or the first request available on list.

void dwc3_gadget_move_started_request(struct dwc3_request *req)¶: move req to the started_list

Parameters

struct dwc3_request *req: the request to be moved

Description

Caller should take care of locking. This function will move req from its current list to the endpoint’s started_list.

void dwc3_gadget_move_cancelled_request(struct dwc3_request *req, unsigned int reason)¶: move req to the cancelled_list

Parameters

struct dwc3_request *req: the request to be moved
unsigned int reason: cancelled reason for the dwc3 request

Description

Caller should take care of locking. This function will move req from its current list to the endpoint’s cancelled_list.

void dwc3_gadget_ep_get_transfer_index(struct dwc3_ep *dep)¶: Gets transfer index from HW

Parameters

struct dwc3_ep *dep: dwc3 endpoint

Description

Caller should take care of locking. Returns the transfer resource index for a given endpoint.

void dwc3_gadget_dctl_write_safe(struct dwc3 *dwc, u32 value)¶: write to DCTL safe from link state change

Parameters

struct dwc3 *dwc: pointer to our context structure
u32 value: value to write to DCTL

Description

Use this function when doing read-modify-write to DCTL. It will not send link state change request.

int dwc3_gadget_set_test_mode(struct dwc3 *dwc, int mode)¶: enables usb2 test modes

Parameters

struct dwc3 *dwc: pointer to our context structure
int mode: the mode to set (J, K SE0 NAK, Force Enable)

Description

Caller should take care of locking. This function will return 0 on success or -EINVAL if wrong Test Selector is passed.

int dwc3_gadget_get_link_state(struct dwc3 *dwc)¶: gets current state of usb link

Parameters

struct dwc3 *dwc: pointer to our context structure

Description

Caller should take care of locking. This function will return the link state on success (>= 0) or -ETIMEDOUT.

int dwc3_gadget_set_link_state(struct dwc3 *dwc, enum dwc3_link_state state)¶: sets usb link to a particular state

Parameters

struct dwc3 *dwc: pointer to our context structure
enum dwc3_link_state state: the state to put link into

Description

Caller should take care of locking. This function will return 0 on success or -ETIMEDOUT.

void dwc3_ep_inc_trb(u8 *index)¶: increment a trb index.

Parameters

u8 *index: Pointer to the TRB index to increment.

Description

The index should never point to the link TRB. After incrementing, if it is point to the link TRB, wrap around to the beginning. The link TRB is always at the last TRB entry.

void dwc3_ep_inc_enq(struct dwc3_ep *dep)¶: increment endpoint’s enqueue pointer

Parameters

struct dwc3_ep *dep: The endpoint whose enqueue pointer we’re incrementing

void dwc3_ep_inc_deq(struct dwc3_ep *dep)¶: increment endpoint’s dequeue pointer

Parameters

struct dwc3_ep *dep: The endpoint whose enqueue pointer we’re incrementing

void dwc3_gadget_giveback(struct dwc3_ep *dep, struct dwc3_request *req, int status)¶: call struct usb_request’s ->complete callback

Parameters

struct dwc3_ep *dep: The endpoint to whom the request belongs to
struct dwc3_request *req: The request we’re giving back
int status: completion code for the request

Description

Must be called with controller’s lock held and interrupts disabled. This function will unmap req and call its ->complete() callback to notify upper layers that it has completed.

int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned int cmd, u32 param)¶: issue a generic command for the controller

Parameters

struct dwc3 *dwc: pointer to the controller context
unsigned int cmd: the command to be issued
u32 param: command parameter

Description

Caller should take care of locking. Issue cmd with a given param to dwc and wait for its completion.

int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd, struct dwc3_gadget_ep_cmd_params *params)¶: issue an endpoint command

Parameters

struct dwc3_ep *dep: the endpoint to which the command is going to be issued
unsigned int cmd: the command to be issued
struct dwc3_gadget_ep_cmd_params *params: parameters to the command

Description

Caller should handle locking. This function will issue cmd with given params to dep and wait for its completion.

int dwc3_gadget_start_config(struct dwc3_ep *dep)¶: configure ep resources

Parameters

struct dwc3_ep *dep: endpoint that is being enabled

Description

Issue a DWC3_DEPCMD_DEPSTARTCFG command to dep. After the command’s completion, it will set Transfer Resource for all available endpoints.

The assignment of transfer resources cannot perfectly follow the data book due to the fact that the controller driver does not have all knowledge of the configuration in advance. It is given this information piecemeal by the composite gadget framework after every SET_CONFIGURATION and SET_INTERFACE. Trying to follow the databook programming model in this scenario can cause errors. For two reasons:

1) The databook says to do DWC3_DEPCMD_DEPSTARTCFG for every USB_REQ_SET_CONFIGURATION and USB_REQ_SET_INTERFACE (8.1.5). This is incorrect in the scenario of multiple interfaces.

2) The databook does not mention doing more DWC3_DEPCMD_DEPXFERCFG for new endpoint on alt setting (8.1.6).

The following simplified method is used instead:

All hardware endpoints can be assigned a transfer resource and this setting will stay persistent until either a core reset or hibernation. So whenever we do a DWC3_DEPCMD_DEPSTARTCFG``(0) we can go ahead and do ``DWC3_DEPCMD_DEPXFERCFG for every hardware endpoint as well. We are guaranteed that there are as many transfer resources as endpoints.

This function is called for each endpoint when it is being enabled but is triggered only when called for EP0-out, which always happens first, and which should only happen in one of the above conditions.

int dwc3_gadget_calc_tx_fifo_size(struct dwc3 *dwc, int mult)¶: calculates the txfifo size value

Parameters

struct dwc3 *dwc: pointer to the DWC3 context
int mult: undescribed

Description

Calculates the size value based on the equation below:

DWC3 revision 280A and prior: fifo_size = mult * (max_packet / mdwidth) + 1;

DWC3 revision 290A and onwards: fifo_size = mult * ((max_packet + mdwidth)/mdwidth + 1) + 1

The max packet size is set to 1024, as the txfifo requirements mainly apply to super speed USB use cases. However, it is safe to overestimate the fifo allocations for other scenarios, i.e. high speed USB.

int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)¶: initializes a hw endpoint

Parameters

struct dwc3_ep *dep: endpoint to be initialized
unsigned int action: one of INIT, MODIFY or RESTORE

Description

Caller should take care of locking. Execute all necessary commands to initialize a HW endpoint so it can be used by a gadget driver.

int __dwc3_gadget_ep_disable(struct dwc3_ep *dep)¶: disables a hw endpoint

Parameters

struct dwc3_ep *dep: the endpoint to disable

Description

This function undoes what __dwc3_gadget_ep_enable did and also removes requests which are currently being processed by the hardware and those which are not yet scheduled.

Caller should take care of locking.

struct dwc3_trb *dwc3_ep_prev_trb(struct dwc3_ep *dep, u8 index)¶: returns the previous TRB in the ring

Parameters

struct dwc3_ep *dep: The endpoint with the TRB ring
u8 index: The index of the current TRB in the ring

Description

Returns the TRB prior to the one pointed to by the index. If the index is 0, we will wrap backwards, skip the link TRB, and return the one just before that.

void dwc3_prepare_one_trb(struct dwc3_ep *dep, struct dwc3_request *req, unsigned int trb_length, unsigned int chain, unsigned int node, bool use_bounce_buffer, bool must_interrupt)¶: setup one TRB from one request

Parameters

struct dwc3_ep *dep: endpoint for which this request is prepared
struct dwc3_request *req: dwc3_request pointer
unsigned int trb_length: buffer size of the TRB
unsigned int chain: should this TRB be chained to the next?
unsigned int node: only for isochronous endpoints. First TRB needs different type.
bool use_bounce_buffer: set to use bounce buffer
bool must_interrupt: set to interrupt on TRB completion

int dwc3_prepare_last_sg(struct dwc3_ep *dep, struct dwc3_request *req, unsigned int entry_length, unsigned int node)¶: prepare TRBs for the last SG entry

Parameters

struct dwc3_ep *dep: The endpoint that the request belongs to
struct dwc3_request *req: The request to prepare
unsigned int entry_length: The last SG entry size
unsigned int node: Indicates whether this is not the first entry (for isoc only)

Description

Return the number of TRBs prepared.

int dwc3_gadget_start_isoc_quirk(struct dwc3_ep *dep)¶: workaround invalid frame number

Parameters

struct dwc3_ep *dep: isoc endpoint

Description

This function tests for the correct combination of BIT[15:14] from the 16-bit microframe number reported by the XferNotReady event for the future frame number to start the isoc transfer.

In DWC_usb31 version 1.70a-ea06 and prior, for highspeed and fullspeed isochronous IN, BIT[15:14] of the 16-bit microframe number reported by the XferNotReady event are invalid. The driver uses this number to schedule the isochronous transfer and passes it to the START TRANSFER command. Because this number is invalid, the command may fail. If BIT[15:14] matches the internal 16-bit microframe, the START TRANSFER command will pass and the transfer will start at the scheduled time, if it is off by 1, the command will still pass, but the transfer will start 2 seconds in the future. For all other conditions, the START TRANSFER command will fail with bus-expiry.

In order to workaround this issue, we can test for the correct combination of BIT[15:14] by sending START TRANSFER commands with different values of BIT[15:14]: ‘b00, ‘b01, ‘b10, and ‘b11. Each combination is 2^14 uframe apart (or 2 seconds). 4 seconds into the future will result in a bus-expiry status. As the result, within the 4 possible combinations for BIT[15:14], there will be 2 successful and 2 failure START COMMAND status. One of the 2 successful command status will result in a 2-second delay start. The smaller BIT[15:14] value is the correct combination.

Since there are only 4 outcomes and the results are ordered, we can simply test 2 START TRANSFER commands with BIT[15:14] combinations ‘b00 and ‘b01 to deduce the smaller successful combination.

Let test0 = test status for combination ‘b00 and test1 = test status for ‘b01 of BIT[15:14]. The correct combination is as follow:

if test0 fails and test1 passes, BIT[15:14] is ‘b01 if test0 fails and test1 fails, BIT[15:14] is ‘b10 if test0 passes and test1 fails, BIT[15:14] is ‘b11 if test0 passes and test1 passes, BIT[15:14] is ‘b00

Synopsys STAR 9001202023: Wrong microframe number for isochronous IN endpoints.

void dwc3_gadget_setup_nump(struct dwc3 *dwc)¶: calculate and initialize NUMP field of DWC3_DCFG

Parameters

struct dwc3 *dwc: pointer to our context structure

Description

The following looks like complex but it’s actually very simple. In order to calculate the number of packets we can burst at once on OUT transfers, we’re gonna use RxFIFO size.

To calculate RxFIFO size we need two numbers: MDWIDTH = size, in bits, of the internal memory bus RAM2_DEPTH = depth, in MDWIDTH, of internal RAM2 (where RxFIFO sits)

Given these two numbers, the formula is simple:

RxFIFO Size = (RAM2_DEPTH * MDWIDTH / 8) - 24 - 16;

24 bytes is for 3x SETUP packets 16 bytes is a clock domain crossing tolerance

Given RxFIFO Size, NUMP = RxFIFOSize / 1024;

int dwc3_gadget_check_config(struct usb_gadget *g)¶: ensure dwc3 can support the USB configuration

Parameters

struct usb_gadget *g: pointer to the USB gadget

Description

Used to record the maximum number of endpoints being used in a USB composite device. (across all configurations) This is to be used in the calculation of the TXFIFO sizes when resizing internal memory for individual endpoints. It will help ensured that the resizing logic reserves enough space for at least one max packet.

int dwc3_gadget_init(struct dwc3 *dwc)¶: initializes gadget related registers

Parameters

struct dwc3 *dwc: pointer to our controller context structure

Description

Returns 0 on success otherwise negative errno.

int dwc3_get_dr_mode(struct dwc3 *dwc)¶: Validates and sets dr_mode

Parameters

struct dwc3 *dwc: pointer to our context structure

int dwc3_core_soft_reset(struct dwc3 *dwc)¶: Issues core soft reset and PHY reset

Parameters

struct dwc3 *dwc: pointer to our context structure

void dwc3_ref_clk_period(struct dwc3 *dwc)¶: Reference clock period configuration Default reference clock period depends on hardware configuration. For systems with reference clock that differs from the default, this will set clock period in DWC3_GUCTL register.

Parameters

struct dwc3 *dwc: Pointer to our controller context structure

void dwc3_free_one_event_buffer(struct dwc3 *dwc, struct dwc3_event_buffer *evt)¶: Frees one event buffer

Parameters

struct dwc3 *dwc: Pointer to our controller context structure
struct dwc3_event_buffer *evt: Pointer to event buffer to be freed

struct dwc3_event_buffer *dwc3_alloc_one_event_buffer(struct dwc3 *dwc, unsigned length)¶: Allocates one event buffer structure

Parameters

struct dwc3 *dwc: Pointer to our controller context structure
unsigned length: size of the event buffer

Description

Returns a pointer to the allocated event buffer structure on success otherwise ERR_PTR(errno).

void dwc3_free_event_buffers(struct dwc3 *dwc)¶: frees all allocated event buffers

Parameters

struct dwc3 *dwc: Pointer to our controller context structure

int dwc3_alloc_event_buffers(struct dwc3 *dwc, unsigned length)¶: Allocates num event buffers of size length

Parameters

struct dwc3 *dwc: pointer to our controller context structure
unsigned length: size of event buffer

Description

Returns 0 on success otherwise negative errno. In the error case, dwc may contain some buffers allocated but not all which were requested.

int dwc3_event_buffers_setup(struct dwc3 *dwc)¶: setup our allocated event buffers

Parameters

struct dwc3 *dwc: pointer to our controller context structure

Description

Returns 0 on success otherwise negative errno.

int dwc3_phy_setup(struct dwc3 *dwc)¶: Configure USB PHY Interface of DWC3 Core

Parameters

struct dwc3 *dwc: Pointer to our controller context structure

Description

Returns 0 on success. The USB PHY interfaces are configured but not initialized. The PHY interfaces and the PHYs get initialized together with the core in dwc3_core_init.

int dwc3_core_init(struct dwc3 *dwc)¶: Low-level initialization of DWC3 Core

Parameters

struct dwc3 *dwc: Pointer to our controller context structure

Description

Returns 0 on success otherwise negative errno.

1(1,2,3): Transfer Request Block
2: Transfer Request Block pointing to another Transfer Request Block.
3(1,2): The Debug File System
4: The Config File System
5: Command Block Wrapper

Synopsys DesignWare Core SuperSpeed USB 3.0 Controller¶

Introduction¶

Summary of Features¶

Driver Design¶

Known Limitations¶

OUT Transfer Size Requirements¶

TRB Ring Size Limitation¶

Reporting Bugs¶

Required Information¶

Debugging¶

DebugFS¶

link_state¶

regdump¶

testmode¶

ep[0..15]{in,out}¶

transfer_type¶

trb_ring¶

Trace Events¶

MMIO¶

Interrupt Events¶

Control Request¶

Lifetime of a struct usb_request¶

Generic Commands¶

Endpoint Commands¶

Lifetime of a TRB¶

Lifetime of an Endpoint¶

Structures, Methods and Definitions¶

`DebugFS`¶

`link_state`¶

`regdump`¶

`testmode`¶

`ep[0..15]{in,out}`¶

`transfer_type`¶

`trb_ring`¶

Lifetime of a `struct usb_request`¶

Lifetime of a `TRB`¶