[Bug 221184] mouse/keyboard (connected via hub) usb reset under system load with weak cpu

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=221184

--- Comment #7 from Alan Stern (stern@rowland.harvard.edu) ---
The usbmon trace shows that your system is getting a lot of communication
errors (multiple errors per second sometimes), probably caused by the system
load as you said.  You can see them yourself in the trace; look for lines
containing a "-71" code, and note that the second column of each line is a
timestamp in microseconds.  (Your computer must be a rather old one for the
load level to affect it this way -- also, the lsusb output shows that the
computer has no USB-3 ports, only USB-2.)

With many of these errors the HID driver simply retries the transfer, and that
works, but sometimes it decides there have been too many errors too rapidly and
it resets the device in an attempt to recover.

As it happens, Liam Mitchell has just submitted a patch to increase the HID
driver's tolerance for these communication errors:

 
https://lore.kernel.org/linux-usb/20260307-usbhid-eproto-v2-1-e5a8abce4652@gmail.com/

I'm not sure how much it will help in your case, because the errors you get
occur so frequently, but it might help some.  Perhaps the patch can be improved
even more.

As for your patch in comment #2...  It is totally the wrong thing to do.  When
an error causes the endpoint to halt, the driver needs to know.  If
qtd_copy_status() returns early for short transfers (which is what your patch
makes it do), the driver won't realize that the endpoint has halted.  To put it
another way, these sorts of errors should not be ignored by ehci-hcd, although
the higher-level HID driver may decide to ignore them.

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