linux-kernel - Re: [PATCH v6 7/8, needs improvement] hid: add suspend/resume hooks for hid drivers

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Message-ID: <20100412185607.10c7b3be@neptune.home>
Date:	Mon, 12 Apr 2010 18:56:07 +0200
From:	Bruno Prémont <bonbons@...ux-vserver.org>
To:	Jiri Kosina <jkosina@...e.cz>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-input@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Rick L. Vinyard Jr." <rvinyard@...nmsu.edu>,
	Nicu Pavel <npavel@...ner.com>,
	Oliver Neukum <oliver@...kum.org>
Subject: Re: [PATCH v6 7/8, needs improvement] hid: add suspend/resume hooks
 for hid drivers

On Mon, 12 April 2010 Jiri Kosina <jkosina@...e.cz> wrote:
> On Sun, 11 Apr 2010, Bruno Prémont wrote:
> 
> > > > As far as I understand the code, in auto-suspend case if the driver 
> > > > sends commands to the device it will have to call usbhid_wait_io(). 
> > > > Please correct me if I'm wrong!
> > > 
> > > It's not needed. There is a queuing mechanism in place on 
> > > 'resumption_waker' workqueue.
> > 
> > So the driver is not allowed to ask the device to do something
> > at auto-suspend time (as that would abort the auto-suspension).
> 
> What do you mean by "is not allowed" exactly?
>
> Yes, it will wake the device up from auto-suspension. However, that's 
> usually what you want to happen, is there is anything you need to dispatch 
> to the device, isn't it?

I thought of a report to send to device to ask the device to disable some
power using feature (e.g. turning off or dimming LEDs)

> What exactly is the situation you are trying to handle?

That's rather a generic question, not related to any implementation.

Maybe I'm mixing suspend and USB-autosuspend too much?

Thanks,
Bruno
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