linux-kernel - Re: [RFC PATCH] input: Add disable sysfs entry for every input device

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Message-ID: <20180103093133.u7wszegjk2msxryl@pali>
Date:   Wed, 3 Jan 2018 10:31:33 +0100
From:   Pali Rohár <pali.rohar@...il.com>
To:     Bastien Nocera <hadess@...ess.net>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
        Sebastian Reichel <sre@...nel.org>,
        Pavel Machek <pavel@....cz>,
        Mauro Carvalho Chehab <mchehab@....samsung.com>,
        Chuck Ebbert <cebbert.lkml@...il.com>,
        Henrik Rydberg <rydberg@...omail.se>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] input: Add disable sysfs entry for every input device

On Wednesday 03 January 2018 02:47:29 Bastien Nocera wrote:
> On Tue, 2018-01-02 at 22:54 +0100, Pali Rohár wrote:
> > On Wednesday 04 January 2017 15:37:35 Bastien Nocera wrote:
> > > I don't doubt that the use cases should be catered for, I
> > > essentially
> > > did that same work without kernel changes for GNOME. What I doubt
> > > is
> > > the fuzzy semantics, the fact that the device is kept opened but no
> > > data is sent (that's not power saving), that whether users are
> > > revoked
> > > or should be revoked isn't clear, and that the goal is basically to
> > > work around stupid input handling when at the console. When running
> > > a
> > > display manager, this is all avoided.
> > > 
> > > If this were to go through, then the semantics and behaviour needs
> > > to
> > > be better explained, power saving actually made possible, and make
> > > sure
> > > that libinput can proxy that state to the users on the console. Or
> > > an
> > > ioctl added to the evdev device to disable them.
> > 
> > So, do you mean to implement this "disable" action as ioctl for
> > particular /dev/input/event* device (instead of sysfs entry)?
> 
> Yes, so the device can be powered down without the device node being
> closed and made unavailable. I don't know whether that's something
> that's already possible for all cases, but there's already
> opportunistic in a lot of drivers and subsystems.
> 
> This opens up a whole new wave of potential problems, but it's a more
> generally useful mechanism, I would think.

Ok. How should API for this ioctl looks like? And do you have an idea
for name of that ioctl?

Dmitry, what do you think about it? It is acceptable for you?

-- 
Pali Rohár
pali.rohar@...il.com