linux-kernel - Re: [PATCH 2/2] platform/chrome: cros_kbd_led_backlight: Remove obsolete commands (EC_CMD_PWM_*_KEYBOARD

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Date: Tue, 26 Mar 2024 10:30:07 +1000
From: Stephen Horvath <s.horvath@...look.com.au>
To: Brian Norris <briannorris@...omium.org>
Cc: Lee Jones <lee@...nel.org>, Benson Leung <bleung@...omium.org>,
 Guenter Roeck <groeck@...omium.org>, Tzung-Bi Shih <tzungbi@...nel.org>,
 chrome-platform@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] platform/chrome: cros_kbd_led_backlight: Remove
 obsolete commands (EC_CMD_PWM_*_KEYBOARD_BACKLIGHT)


On 26/3/24 04:45, Brian Norris wrote:
> Just because the EC firmware repository marks these as obsolete (and
> yes, we copy that header mostly as-is into the kernel repository ...
> but it's still a firmware header) doesn't mean it's truly ready to be
> removed. I believe the intention is to direct *firmware* developers
> not to use them -- any new developments should be using the new
> commands.
> 
> From a kernel perspective, we could still be supporting old firmware
> on old devices, and so we may want/need to continue to support these
> commands.

Alright that makes sense.

> I don't know off the top of my head which firmware branches support
> which commands, on devices that have such keyboard backlights. (The
> Chromium EC repository is open source though, with various firmware-*
> branches still around, so this information is available.) But without
> a better explanation as to why these are truly ready to be removed,
> I'll say "NAK."

Yeah that's fair enough, my laptop seems to support both so I'll agree 
the older commands are probably the safer option.

Thanks a lot for your feedback!
Steve