Re: [PATCH v3] USB: HID: random timeout failures tackle try.

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Feb 04, 2020 at 03:15:56PM +0200, Lauri Jakku wrote:
> There is multiple reports of random behaviour of USB HID devices.
> 
> I have mouse that acts sometimes quite randomly, I debugged with
> logs others have published: that there is HW timeouts that leave
> device in state that it is errorneus.
> 
> To fix this, I introduce retry mechanism in root of USB HID drivers.
> 
> Fix does not slow down operations at all if there is no -ETIMEDOUT
> got from control message sending.
> 
> If there is one, then sleep 20ms and try again. Retry count is 20
> witch translates maximium of 400ms before giving up. If the 400ms
> boundary is reached the HW is really bad.
> 
> JUST to be clear:
>     This does not make USB HID devices to sleep anymore than
>     before, if all is golden and no timeouts are got.
> 
> Why modify usb-hid-core: No need to modify driver by driver.
> At this time i do not know all the USB HID devices that timeouts,
> but what i've researched, there are issues.
> 
> Timeout given is divided by 100, but taken care that it is always
> at least 10ms.
> 
> so total time in common worst-case-scenario is:
> 
>  sleep of 20ms + common timeout divided by 100 (50ms) makes
>  70ms per loop, 20 loops => 1.4sec .
> 
> Signed-off-by: Lauri Jakku <lja@iki.fi>
> ---
>  drivers/usb/core/message.c | 55 ++++++++++++++++++++++++++++++++++----
>  1 file changed, 50 insertions(+), 5 deletions(-)

What changed from v1 and v2?

That always has to be described below the --- line, as documented, to
give us a chance to understand what is happening here and why this is a
new version.

Please fix up and send a v4.

thanks,

greg k-h