linux-kernel - Re: [PATCH 3/3] HID: usbhid: defer LED setting to a workqueue

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Date:	Wed, 14 Dec 2011 12:22:40 +0100
From:	Oliver Neukum <oneukum@...e.de>
To:	Daniel Kurtz <djkurtz@...omium.org>
Cc:	jkosina@...e.cz, bleung@...omium.org, stern@...land.harvard.edu,
	olofj@...omium.org, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH 3/3] HID: usbhid: defer LED setting to a workqueue

Am Mittwoch, 14. Dezember 2011, 11:33:03 schrieb Daniel Kurtz:
> On Wed, Dec 14, 2011 at 4:01 PM, Oliver Neukum <oneukum@...e.de> wrote:
> > Am Donnerstag, 17. November 2011, 12:23:50 schrieb Daniel Kurtz:
> >> Defer LED setting action to a workqueue.
> >> This is more likely to send all LED change events in a single URB.
> >
> > Hi,
> >
> > I hope I am looking at the correct version of this patch.
> > But as far as I can see the work for handling LEDs is not delayed
> > while a reset is going on. That is wrong.
> 
> Actually, I'm not sure why this is wrong.  I find the reset handling
> quite confusing in this driver.
> Can you point out what will fail, and recommend how to fix it?

That is part of the workings of a USB driver. After you return from
pre_reset() you don't do IO to the device. After post_reset() the
device should be in its default state whose LED states won't match
what they ought to be.

	Regards
		Oliver
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