Re: [PATCH v2] leds: trigger: audio: Add an activate callback to ensure the initial brightness is set

[Takashi Iwai <tiwai@suse.de>]

On Sun, 21 Feb 2021 12:52:08 +0100,
Hans de Goede wrote:
> 
> Some 2-in-1s with a detachable (USB) keyboard(dock) have mute-LEDs in
> the speaker- and/or mic-mute keys on the keyboard.
> 
> Examples of this are the Lenovo Thinkpad10 tablet (with its USB kbd-dock)
> and the HP x2 10 series.
> 
> The detachable nature of these keyboards means that the keyboard and
> thus the mute LEDs may show up after the user (or userspace restoring
> old mixer settings) has muted the speaker and/or mic.
> 
> Current LED-class devices with a default_trigger of "audio-mute" or
> "audio-micmute" initialize the brightness member of led_classdev with
> ledtrig_audio_get() before registering the LED.
> 
> This makes the software state after attaching the keyboard match the
> actual audio mute state, e.g. cat /sys/class/leds/foo/brightness will
> show the right value.
> 
> But before this commit nothing was actually calling the led_classdev's
> brightness_set[_blocking] callback so the value returned by
> ledtrig_audio_get() was never actually being sent to the hw, leading
> to the mute LEDs staying in their default power-on state, after
> attaching the keyboard, even if ledtrig_audio_get() returned a different
> state.
> 
> This could be fixed by having the individual LED drivers call
> brightness_set[_blocking] themselves after registering the LED,
> but this really is something which should be done by a led-trigger
> activate callback.
> 
> Add an activate callback for this, fixing the issue of the
> mute LEDs being out of sync after (re)attaching the keyboard.
> 
> Cc: Takashi Iwai <tiwai@suse.de>
> Fixes: faa2541f5b1a ("leds: trigger: Introduce audio mute LED trigger")
> Reviewed-by: Marek Behún <kabel@kernel.org>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
> Changes in v2:
> - Fix a couple of grammar errors in the commit-message
> - Add Marek's Reviewed-by (thank you)

Looks good to me, thanks!
Reviewed-by: Takashi Iwai <tiwai@suse.de>


Takashi

> ---
>  drivers/leds/trigger/ledtrig-audio.c | 37 ++++++++++++++++++++++------
>  1 file changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/leds/trigger/ledtrig-audio.c b/drivers/leds/trigger/ledtrig-audio.c
> index f76621e88482..c6b437e6369b 100644
> --- a/drivers/leds/trigger/ledtrig-audio.c
> +++ b/drivers/leds/trigger/ledtrig-audio.c
> @@ -6,10 +6,33 @@
>  #include <linux/kernel.h>
>  #include <linux/leds.h>
>  #include <linux/module.h>
> +#include "../leds.h"
>  
> -static struct led_trigger *ledtrig_audio[NUM_AUDIO_LEDS];
>  static enum led_brightness audio_state[NUM_AUDIO_LEDS];
>  
> +static int ledtrig_audio_mute_activate(struct led_classdev *led_cdev)
> +{
> +	led_set_brightness_nosleep(led_cdev, audio_state[LED_AUDIO_MUTE]);
> +	return 0;
> +}
> +
> +static int ledtrig_audio_micmute_activate(struct led_classdev *led_cdev)
> +{
> +	led_set_brightness_nosleep(led_cdev, audio_state[LED_AUDIO_MICMUTE]);
> +	return 0;
> +}
> +
> +static struct led_trigger ledtrig_audio[NUM_AUDIO_LEDS] = {
> +	[LED_AUDIO_MUTE] = {
> +		.name     = "audio-mute",
> +		.activate = ledtrig_audio_mute_activate,
> +	},
> +	[LED_AUDIO_MICMUTE] = {
> +		.name     = "audio-micmute",
> +		.activate = ledtrig_audio_micmute_activate,
> +	},
> +};
> +
>  enum led_brightness ledtrig_audio_get(enum led_audio type)
>  {
>  	return audio_state[type];
> @@ -19,24 +42,22 @@ EXPORT_SYMBOL_GPL(ledtrig_audio_get);
>  void ledtrig_audio_set(enum led_audio type, enum led_brightness state)
>  {
>  	audio_state[type] = state;
> -	led_trigger_event(ledtrig_audio[type], state);
> +	led_trigger_event(&ledtrig_audio[type], state);
>  }
>  EXPORT_SYMBOL_GPL(ledtrig_audio_set);
>  
>  static int __init ledtrig_audio_init(void)
>  {
> -	led_trigger_register_simple("audio-mute",
> -				    &ledtrig_audio[LED_AUDIO_MUTE]);
> -	led_trigger_register_simple("audio-micmute",
> -				    &ledtrig_audio[LED_AUDIO_MICMUTE]);
> +	led_trigger_register(&ledtrig_audio[LED_AUDIO_MUTE]);
> +	led_trigger_register(&ledtrig_audio[LED_AUDIO_MICMUTE]);
>  	return 0;
>  }
>  module_init(ledtrig_audio_init);
>  
>  static void __exit ledtrig_audio_exit(void)
>  {
> -	led_trigger_unregister_simple(ledtrig_audio[LED_AUDIO_MUTE]);
> -	led_trigger_unregister_simple(ledtrig_audio[LED_AUDIO_MICMUTE]);
> +	led_trigger_unregister(&ledtrig_audio[LED_AUDIO_MUTE]);
> +	led_trigger_unregister(&ledtrig_audio[LED_AUDIO_MICMUTE]);
>  }
>  module_exit(ledtrig_audio_exit);
>  
> -- 
> 2.30.1
>