b3eb981be7
When handling split transactions we will try to delay retry after
getting a NAK from the device. This works well for BULK transfers that
can be polled for essentially forever. Unfortunately, on slower systems
at boot time, when the kernel is busy enumerating all the devices (USB
or not), we issue a bunch of control requests (reading device
descriptors, etc). If we get a NAK for the IN part of the control
request and delay retry for too long (because the system is busy), we
may confuse the device when we finally get to reissue SSPLIT/CSPLIT IN
and the device will respond with STALL. As a result we end up with
failure to get device descriptor and will fail to enumerate the device:
[ 3.428801] usb 2-1.2.1: new full-speed USB device number 9 using dwc2
[ 3.508576] usb 2-1.2.1: device descriptor read/8, error -32
[ 3.699150] usb 2-1.2.1: device descriptor read/8, error -32
[ 3.891653] usb 2-1.2.1: new full-speed USB device number 10 using dwc2
[ 3.968859] usb 2-1.2.1: device descriptor read/8, error -32
...
Let's not delay retries of split CONTROL IN transfers, as this allows us
to reliably enumerate devices at boot time.
Fixes: 38d2b5fb75c1 ("usb: dwc2: host: Don't retry NAKed transactions right away")
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.