linux-kernel - RE: [PATCH v2] Input: hyperv-keyboard: Add the support of hibernation

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Message-ID: <CY4PR21MB0629E445FB3D5A3EC58DC494D74B0@CY4PR21MB0629.namprd21.prod.outlook.com>
Date:   Sun, 24 Nov 2019 20:31:01 +0000
From:   Michael Kelley <mikelley@...rosoft.com>
To:     Dexuan Cui <decui@...rosoft.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "sashal@...nel.org" <sashal@...nel.org>,
        "dmitry.torokhov@...il.com" <dmitry.torokhov@...il.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: RE: [PATCH v2] Input: hyperv-keyboard: Add the support of hibernation

From: Dexuan Cui <decui@...rosoft.com> Sent: Tuesday, November 19, 2019 11:14 PM
> 
> During the suspend process and resume process, if there is any keyboard
> event, there is a small chance the suspend and the resume process can be
> aborted because of hv_kbd_on_receive() -> pm_wakeup_hard_event().
> 
> This behavior can be avoided by disabling the Hyper-V keyboard device as
> a wakeup source:
> 
> echo disabled > /sys/bus/vmbus/drivers/hyperv_keyboard/XXX/power/wakeup
> (XXX is the device's GUID).

I'd like to see a more descriptive commit message, along the lines of:

Add suspend() and resume() functions so the Hyper-V virtual keyboard
can participate in VM hibernation.

Note that the keyboard is a "wakeup" device that could abort an in-progress
hibernation if there is keyboard event.  No attempt is made to suppress this
behavior.  If desired, a sysadmin can disable the keyboard as a wakeup device
using standard mechanisms such as:

echo disabled > /sys/bus/vmbus/drivers/hyperv_keyboard/XXX/power/wakeup
(where XXX is the device's GUID)

> 
> Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> ---
> 
> This patch is basically a pure Hyper-V specific change. I suggest it should
> go through the Hyper-V tree:
> https://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git/log/?h=hyperv-next
> 
> Changes in v2:
>   Removed the "struct notifier_block pm_nb;" after the discussion
> with Dmitry Torokhov:
> 
> https://lore.kernel.org/lkml/PU1P153MB016914A7C827CA35D7FEB66ABF8B0@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM/T/#m8948c711301220a36a1a413eead74cd2fb6dcac1> 
>
>  drivers/input/serio/hyperv-keyboard.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 

Notwithstanding the suggestion on the commit message,

Reviewed-by:  Michael Kelley <mikelley@...rosoft.com>