Re: [PATCH] HID: usbhid: get/put around clearing needs_remote_wakeup

From: Benson Leung
Date: Fri Nov 21 2014 - 20:00:55 EST

On Fri, Nov 14, 2014 at 1:08 AM, Oliver Neukum <oneukum@xxxxxxx> wrote:
> On Thu, 2014-11-13 at 12:16 -0800, Benson Leung wrote:
>> In usbhid_open, usb_autopm_get_interface is called
>> before setting the needs_remote_wakeup flag, and
>> usb_autopm_put_interface is called after hid_start_in.
>> However, when the device is closed in usbhid_close, the same
>> protection isn't there when clearing needs_remote_wakeup. This will
>> add that to usbhid_close as well as usbhid_stop.
> Interesting, but this has the side effect of waking devices
> that are asleep just to remove the flag.
> Regards

If devices are already asleep with this flag enabled, that means that
they are presently configured for remote wake.

Waking the device in the case of a close() is appropriate because it
also has the effect of re-suspending the device with the capability
disabled, as it is no longer necessary.

Benson Leung
Software Engineer, Chrom* OS
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