linux-kernel - Re: [PATCH] HID: quirks: Disable runtime suspend on Microsoft Corp. Basic Optical Mouse v2.0

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Message-Id: <AD8A4135-0275-45B3-BEB9-031737A2C756@canonical.com>
Date:   Thu, 22 Aug 2019 18:04:44 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Oliver Neukum <oneukum@...e.com>
Cc:     jikos@...nel.org, benjamin.tissoires@...hat.com,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH] HID: quirks: Disable runtime suspend on Microsoft Corp.
 Basic Optical Mouse v2.0

Hi Oliver,

at 17:45, Oliver Neukum <oneukum@...e.com> wrote:

> Am Donnerstag, den 22.08.2019, 17:17 +0800 schrieb Kai-Heng Feng:
>> The optical sensor of the mouse gets turned off when it's runtime
>> suspended, so moving the mouse can't wake the mouse up, despite that
>> USB remote wakeup is successfully set.
>>
>> Introduce a new quirk to prevent the mouse from getting runtime
>> suspended.
>
> Hi,
>
> I am afraid this is a bad approach in principle. The device
> behaves according to spec.

Can you please point out which spec it is? Is it USB 2.0 spec?

> And it behaves like most hardware.

So seems like most hardware are broken.
Maybe a more appropriate solution is to disable RPM for all USB mice.

> If you do not want runtime PM for such devices, do not switch
> it on.

A device should work regardless of runtime PM status.

> The refcounting needs to be done correctly.

Will do.

>
> This patch does something that udev should do and in a
> questionable manner.

IMO if the device doesn’t support runtime suspend, then it needs to be  
disabled in kernel but not workaround in userspace.

Kai-Heng

>
> 	Regards
> 		Oliver