Re: [PATCH] platform/chrome: cros_kbd_led_backlight: enable probing through EC_FEATURE_PWM_KEYB

[Tzung-Bi Shih <tzungbi@kernel.org>]

On Mon, May 06, 2024 at 07:38:09PM +0200, Thomas Weißschuh wrote:
> On 2024-05-05 08:42:21+0000, Mario Limonciello wrote:
> > On 5/5/2024 04:41, Thomas Weißschuh wrote:
> > > The ChromeOS EC used in Framework laptops supports the standard cros
> > > keyboard backlight protocol.
> > > However the firmware on these laptops don't implement the ACPI ID
> > > GOOG0002 that is recognized by cros_kbd_led_backlight and they also
> > > don't use device tree.

If implementing ACPI ID GOOG0002 is not an option, how about adding a new ACPI
ID?  For the new ACPI ID, it can use EC PWM for setting the brightness.

> > Something I'd wonder is if the GOOG0002 ACPI ID can go away entirely with
> > this type of change.  Presumably the Chromebooks with ChromeOS EC /also/
> > advertise EC_FEATURE_PWM_KEYB.
> 
> Sounds good to me in general. It would make the code cleaner.
> 
> But I have no idea how CrOS kernels are set up in general.
> If they are not using CONFIG_MFD_CROS_EC_DEV for some reason that
> wouldn't work.
> 
> If the CrOS folks agree with that aproach I'll be happy to implement it.

I would say NO as some existing devices (with legacy firmware and kernel) may
rely on it.