[PATCH] vt: keyboard: Use led_set_brightness() in LED trigger activate() callback

[PATCH] vt: keyboard: Use led_set_brightness() in LED trigger activate() callback

[Hans de Goede]

A LED trigger's activate() callback gets called when the LED trigger
gets activated for a specific LED, so that the trigger code can ensure
the LED state matches the current state of the trigger condition.

led_trigger_event() is intended for trigger condition state changes and
iterates over _all_ LEDs which are controlled by this trigger changing
the brightness of each of them.

In the activate() case only the brightness of the LED which is being
activated needs to change and that LED is passed as an argument to
activate(), switch to led_set_brightness() to only change the brightness
of the LED being activated.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/tty/vt/keyboard.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index a2116e135a82..804355da46f5 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -1033,9 +1033,7 @@ static int kbd_led_trigger_activate(struct led_classdev *cdev)
 
 	tasklet_disable(&keyboard_tasklet);
 	if (ledstate != -1U)
-		led_trigger_event(&trigger->trigger,
-				  ledstate & trigger->mask ?
-					LED_FULL : LED_OFF);
+		led_set_brightness(cdev, ledstate & trigger->mask ? LED_FULL : LED_OFF);
 	tasklet_enable(&keyboard_tasklet);
 
 	return 0;
-- 
2.44.0

Re: [PATCH] vt: keyboard: Use led_set_brightness() in LED trigger activate() callback

[Jiri Slaby]

On 11. 05. 24, 17:20, Hans de Goede wrote:
> A LED trigger's activate() callback gets called when the LED trigger
> gets activated for a specific LED, so that the trigger code can ensure
> the LED state matches the current state of the trigger condition.
> 
> led_trigger_event() is intended for trigger condition state changes and
> iterates over _all_ LEDs which are controlled by this trigger changing
> the brightness of each of them.
> 
> In the activate() case only the brightness of the LED which is being
> activated needs to change and that LED is passed as an argument to
> activate(), switch to led_set_brightness() to only change the brightness
> of the LED being activated.

LGTM, but could you elaborate on what behavior this fixes? Should it be 
backported to stable?

> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>   drivers/tty/vt/keyboard.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
> index a2116e135a82..804355da46f5 100644
> --- a/drivers/tty/vt/keyboard.c
> +++ b/drivers/tty/vt/keyboard.c
> @@ -1033,9 +1033,7 @@ static int kbd_led_trigger_activate(struct led_classdev *cdev)
>   
>   	tasklet_disable(&keyboard_tasklet);
>   	if (ledstate != -1U)
> -		led_trigger_event(&trigger->trigger,
> -				  ledstate & trigger->mask ?
> -					LED_FULL : LED_OFF);
> +		led_set_brightness(cdev, ledstate & trigger->mask ? LED_FULL : LED_OFF);
>   	tasklet_enable(&keyboard_tasklet);
>   
>   	return 0;

thanks,
-- 
js

Re: [PATCH] vt: keyboard: Use led_set_brightness() in LED trigger activate() callback

[Hans de Goede]

Hi Jiri,

On 5/13/24 7:09 AM, Jiri Slaby wrote:
> On 11. 05. 24, 17:20, Hans de Goede wrote:
>> A LED trigger's activate() callback gets called when the LED trigger
>> gets activated for a specific LED, so that the trigger code can ensure
>> the LED state matches the current state of the trigger condition.
>>
>> led_trigger_event() is intended for trigger condition state changes and
>> iterates over _all_ LEDs which are controlled by this trigger changing
>> the brightness of each of them.
>>
>> In the activate() case only the brightness of the LED which is being
>> activated needs to change and that LED is passed as an argument to
>> activate(), switch to led_set_brightness() to only change the brightness
>> of the LED being activated.
> 
> LGTM, but could you elaborate on what behavior this fixes? Should it be backported to stable?

It does not really fix any user visible behavior. This is just something which
I noticed while looking at all LED trigger activate callbacks because of some
LED core patches I was writing.

The code before this patch gets the job done, it syncs the VT capslock/numlock/etc
status to the LEDs of a newly registered input device.

But it also ends up calling led_set_brightness() on all already registered
capslock/numlock/etc LEDs which is not necessary.

So this is just a small optimization, not a bug fix.

Regards,

Hans


> 
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>> ---
>>   drivers/tty/vt/keyboard.c | 4 +---
>>   1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
>> index a2116e135a82..804355da46f5 100644
>> --- a/drivers/tty/vt/keyboard.c
>> +++ b/drivers/tty/vt/keyboard.c
>> @@ -1033,9 +1033,7 @@ static int kbd_led_trigger_activate(struct led_classdev *cdev)
>>         tasklet_disable(&keyboard_tasklet);
>>       if (ledstate != -1U)
>> -        led_trigger_event(&trigger->trigger,
>> -                  ledstate & trigger->mask ?
>> -                    LED_FULL : LED_OFF);
>> +        led_set_brightness(cdev, ledstate & trigger->mask ? LED_FULL : LED_OFF);
>>       tasklet_enable(&keyboard_tasklet);
>>         return 0;
> 
> thanks,

Re: [PATCH] vt: keyboard: Use led_set_brightness() in LED trigger activate() callback

[Jiri Slaby]

On 11. 05. 24, 17:20, Hans de Goede wrote:
> A LED trigger's activate() callback gets called when the LED trigger
> gets activated for a specific LED, so that the trigger code can ensure
> the LED state matches the current state of the trigger condition.
> 
> led_trigger_event() is intended for trigger condition state changes and
> iterates over _all_ LEDs which are controlled by this trigger changing
> the brightness of each of them.
> 
> In the activate() case only the brightness of the LED which is being
> activated needs to change and that LED is passed as an argument to
> activate(), switch to led_set_brightness() to only change the brightness
> of the LED being activated.
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>

thanks,
-- 
js
suse labs