linux-kernel - Re: [PATCH v5 1/1] Input: cros_ec_keyb

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Message-ID: <aYo2cYhd-XCcLa43@google.com>
Date: Mon, 9 Feb 2026 19:33:05 +0000
From: Fabio Baltieri <fabiobaltieri@...omium.org>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: Benson Leung <bleung@...omium.org>, Guenter Roeck <groeck@...omium.org>,
	Tzung-Bi Shih <tzungbi@...nel.org>, Simon Glass <sjg@...omium.org>,
	linux-input@...r.kernel.org, chrome-platform@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/1] Input: cros_ec_keyb - add function key support

On Mon, Feb 09, 2026 at 10:20:52AM -0800, Dmitry Torokhov wrote:
> On Mon, Feb 09, 2026 at 03:46:20PM +0000, Fabio Baltieri wrote:
> > On Fri, Feb 06, 2026 at 08:25:14AM -0800, Dmitry Torokhov wrote:
> > > 
> > > I do not believe this flag is needed. Always do FN processing. If there
> > > is no FN in the keymap it should work just fine.
> > 
> > The problem is that if there is an Fn key and a keymap, hence we process
> > the Fn keys in the kernel, then we don't send the Fn events, but we
> > currently have devices deployed with an Fn key where the key is handled
> > by the userspace and they expect KEY_FN events to be emitted, so if I
> > let the "fn keymap" logic kick in it unconditionally it would cause a
> > regression for existing devices.
> 
> Hmm, I see. Then I think we really need to have it as a device property,
> because keymap can be manipulated at runtime, so depending on it to
> switch processing seems weird.
> 
> It is like autorepeat, either device configuration asks for it, or it
> does not...

Ok, the DT folks were fairly explicit about not wanting anything that
even remotely looks like configuration into dt. Right now the behavior
changes based on what's in the keymap, which I think is fine.

I see the keymap can be manipulated in runtime but then I guess I could
just install a custom hook to idev->setkeycode, recompute
cros_ec_keyb_has_fn_map() and then call input_default_getkeycode()?
I'd have to make that function public but then it'd automatically change
the behavior in runtime as keycodes are defined/undefined.

Would that be acceptable?