linux-kernel - Re: [PATCH] hid: enable hid device to suspend/resume asynchronously

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Message-ID: <alpine.LNX.2.00.1509251404130.30132@pobox.suse.cz>
Date:	Fri, 25 Sep 2015 14:05:41 +0200 (CEST)
From:	Jiri Kosina <jikos@...nel.org>
To:	"Fu, Zhonghui" <zhonghui.fu@...ux.intel.com>
cc:	linux-input@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] hid: enable hid device to suspend/resume
 asynchronously

On Thu, 24 Sep 2015, Fu, Zhonghui wrote:

> >> Enable hid device to suspend/resume asynchronously. This can improve
> >> system suspend/resume speed.
> > How well was this tested?
> >
> > Power management is notorious for not being really in excellent shape on 
> > many HID devices.
> >
> > So I'd like to be careful.
> I were on leave these days, so sorry for late reply.
> 
> This can reduce system suspend/resume time about 20ms, from 1030ms to 
> 1010ms on ASUS T100TA machine. Although the improvement is not very 
> significant, but this can let your parent/child device suspend/resume 
> more asynchronously and take advantage of multicore to improve overall 
> system suspend/resume speed.
> 
> I have resent this patch with updated commit message - "[PATCH v2] hid: 
> enable hid device to suspend/resume asynchronously".

Is there any reason why not enable this from userspace via sysfs instead, 
based on whitelist on known-to-be-well-behaved devices, from udev?

I am really careful when it comes to enabling features like this 
(especially given the state of PM support on some low-end devices) 
globally.

Thanks,

-- 
Jiri Kosina
SUSE Labs

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