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From: Alan Stern <stern@rowland.harvard.edu>
To: Lauri Jakku <lja@iki.fi>
Cc: oneukum@suse.com, <benjamin.tissoires@redhat.com>,
	<jikos@kernel.org>, <linux-input@vger.kernel.org>,
	<gregkh@linuxfoundation.org>, <linux-usb@vger.kernel.org>
Subject: Re: [PATCH v5] USB: HID: random timeout failures tackle try.
Date: Tue, 4 Feb 2020 13:07:31 -0500 (EST)	[thread overview]
Message-ID: <Pine.LNX.4.44L0.2002041306100.1587-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <20200204175238.3817-1-lja@iki.fi>

On Tue, 4 Feb 2020, Lauri Jakku wrote:

> -- v1 ------------------------------------------------------------
> send, 20ms apart, control messages, if error is timeout.
> 
> 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 introduced 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.
> 
> NOTE: This does not sleep anymore then before, if all is golden.
> 
> -- v2 ------------------------------------------------------------
> 
> If there is timeout, 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.
> 
> Why modify usb-hid-core: No need to modify driver by driver.

Please note: Your patch does _not_ modify usb-hid-core (that is, 
drivers/hid/usbhid).  It modifies usb-core (that is, drivers/usb/core).

Alan Stern


  reply	other threads:[~2020-02-04 18:07 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-04 17:52 [PATCH v5] USB: HID: random timeout failures tackle try Lauri Jakku
2020-02-04 18:07 ` Alan Stern [this message]
2020-02-04 20:14   ` Lauri Jakku
2020-02-04 18:11 ` Greg KH
2020-02-04 18:15 ` Greg KH
2020-02-04 20:05   ` Lauri Jakku
2020-02-05 10:03 ` Oliver Neukum

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