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

From: Jiri Kosina
Date: Tue Jul 29 2014 - 05:12:23 EST

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@xxxxxxxxxxxxx>
> > Signed-off-by: Vincent Huang <vincent.huang@xxxxxxxxxxxxxxxx>
> > ---
> > 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@xxxxxxxxxx>

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


Jiri Kosina
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