linux-kernel - Re: [PATCH] HID: i2c-hid: call the hid driver's suspend and resume callbacks

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Date:	Tue, 29 Jul 2014 11:11:53 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Benjamin Tissoires <benjamin.tissoires@...hat.com>
cc:	Andrew Duggan <aduggan@...aptics.com>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Vincent Huang <vincent.huang@...synaptics.com>,
	Mika Westerberg <mika.westerberg@...el.com>
Subject: Re: [PATCH] HID: i2c-hid: call the hid driver's suspend and resume
 callbacks

On Thu, 17 Jul 2014, Benjamin Tissoires wrote:

> > Currently, the i2c-hid driver does not call the suspend, resume, and
> > reset_resume callbacks in the hid_driver struct when those events occur.
> > This means that HID drivers for i2c-hid devices will not be able to execute
> > commands which may be needed during suspend or resume. One example is when a
> > touchpad using the hid-multitouch driver gets reset by i2c-hid coming out of
> > resume. Since the reset_resume callback never gets called the device is never
> > put back into the correct input mode. This patch calls the suspend and resume
> > callbacks and tries to duplicate the functionality of the usb-hid driver.
> > 
> > Signed-off-by: Andrew Duggan <aduggan@...aptics.com>
> > Signed-off-by: Vincent Huang <vincent.huang@...synaptics.com>
> > ---
> > Hi Benjamin,
> > 
> > This is the patch which Vincent and I came up with to fix the behavior which we were seeing with touchpads not being operational after resuming. We only use the reset_resume callback since i2c_hid_resume is always doing a hardware reset and it doesn't seem like there is a condition in which the standard resume callback would be appropriate. Also, is a full hardware reset always needed when resuming?
> 
> Hi Andrew,
> 
> well, the PM management of i2c_hid has been handled by Mika (in CC) and
> I am unfortunately not able to have a strong opinion on this. I still
> lack of hardware properly supporting the suspend/resume mechanism.
> 
> So, you are in charge of that. IIRC, nothing prevents from not calling
> hw_reset, but I guess this was the safer implementation we could have.
> 
> Anyway, the patch looks good:
> Reviewed-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>

I am queuing this for 3.17. Mika, if you have any objections, please speak 
up.

Thanks,

-- 
Jiri Kosina
SUSE Labs
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