linux-kernel - Re: [PATCH v4 1/2] Input: Add a Kconfig to emulate KEY

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Message-ID: <owigkmidrmavvcdewxx3fvqyp4klvchklgwbtpzncqiado4kwb@akuzxqxp5jpm>
Date: Sun, 27 Apr 2025 22:51:32 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Mario Limonciello <superm1@...nel.org>
Cc: Pavel Machek <pavel@....cz>, 
	Shyam Sundar S K <Shyam-sundar.S-k@....com>, Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, 
	Hans de Goede <hdegoede@...hat.com>, 
	"open list:INPUT (KEYBOARD, MOUSE, JOYSTICK, TOUCHSCREEN)..." <linux-input@...r.kernel.org>, open list <linux-kernel@...r.kernel.org>, 
	"open list:AMD PMF DRIVER" <platform-driver-x86@...r.kernel.org>, Mario Limonciello <mario.limonciello@....com>, 
	Armin Wolf <W_Armin@....de>
Subject: Re: [PATCH v4 1/2] Input: Add a Kconfig to emulate KEY_SCREENLOCK
 with META + L

On Sun, Apr 27, 2025 at 10:30:24PM -0700, Dmitry Torokhov wrote:
> Apologies for extended absence...
> 
> On Sun, Apr 27, 2025 at 07:15:31AM -0500, Mario Limonciello wrote:
> > 
> > 
> > On 4/27/25 01:10, Pavel Machek wrote:
> > > Hi!
> > > 
> > > > > > > > In the PC industry KEY_SCREENLOCK isn't used as frequently as it used
> > > > > > > > to be. Modern versions of Windows [1], GNOME and KDE support "META" + "L"
> > > > > > > > to lock the screen. Modern hardware [2] also sends this sequence of
> > > > > > > > events for keys with a silkscreen for screen lock.
> > > > > > > > 
> > > > > > > > Introduced a new Kconfig option that will change KEY_SCREENLOCK when
> > > > > > > > emitted by driver to META + L.
> > > > > > > 
> > > > > > > Fix gnome and kde, do not break kernel...
> > > > > > 
> > > > > > I'm sorry; fix them to do what exactly?  Switch to KEY_SCREENLOCK?
> > > > > > 
> > > > > > That's going to break modern hardware lockscreen keys.  They've all
> > > > > > obviously moved to META+L because that's what hardware today uses.
> 
> Vendors do all kind of weird things. They want to ship their
> peripherals here and now and they do not care of shortcuts will change a
> few years down the road.
> 
> FWIW there are plenty of external keyboards that use KEY_SCREENLOCK and
> do not emit any shortcurts. Anything that is "Woks with Chromebooks"
> will use KEY_SCREENLOCK.
> 
> 
> > > > > 
> > > > > Gnome / KDE should accept either META+L _or_ KEY_SCREENLOCK to do the
> > > > > screen locking, no?
> 
> KDE by default recognizes Meta+L combination (which used to be
> Alt+Ctrl+L), Screensaver key, and allows users to define their custom
> shortcuts.
> 
> I also wonder how many other DEs beside Gnome do not recognize
> KEY_SCREENLOCK.

So I poked around Gnome a bit. According to the gnome-settings-daemon
source code KEY_SCREENLOCK should be recognized. It is set up as
"screensaver-static" key which is hidden and shoudl not be changed by
user:

https://github.com/GNOME/gnome-settings-daemon/blob/master/data/org.gnome.settings-daemon.plugins.media-keys.gschema.xml.in#L504

    <key name="screensaver-static" type="as">
      <default>['XF86ScreenSaver']</default>
      <summary>Lock screen</summary>
      <description>Static binding to lock the screen.</description>
    </key>



> 
> > > > 
> > > > This was actually the first path I looked down before I even started the
> > > > kernel patch direction for this problem.
> > > > 
> > > > GNOME doesn't support assigning more than one shortcut key for an action.

It sure does even if it is not shown in UI. Poke around with
dconf-editor and look in /org/gnome/settings-daemon/plugins/media-keys/
and you will see plenty of "*-static" keys with multiple
keycodes/shortcuts assigned.

"touchpad-toggle-static" - ['XF86TouchpadToggle', '<Ctrl><Super>XF86TouchpadToggle']
"rotate-video-lock-static" - ['<Super>o', 'XF86RotationLockToggle']

and so on...

Maybe Gnome broke screen lock key in recent release?

Thanks.

-- 
Dmitry