linux-kernel - Re: [PATCH 2/2] leds: fix led_brightness

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Date:	Wed, 6 Jun 2012 11:58:10 +0800
From:	Bryan Wu <bryan.wu@...onical.com>
To:	Fabio Baltieri <fabio.baltieri@...il.com>
Cc:	linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
	Richard Purdie <rpurdie@...ys.net>
Subject: Re: [PATCH 2/2] leds: fix led_brightness_set when soft-blinking

On Wed, Jun 6, 2012 at 5:38 AM, Fabio Baltieri <fabio.baltieri@...il.com> wrote:
> Change led_brightness_set to ensure software blink timer is stopped
> before calling led_stop_software_blink() and use led_set_brightness()
> instead of calling led_cdev->brightness_set() directly to ensure
> led_cdev->brightness is always consistent with current LED status.
>
> This ensure proper cleaning when changing triggers, as without this fix
> a LED may be turned off while leaving it's led_cdev->brightness = 1,
> leading to an erratic software-blink behaviour.
>
> The problem was easy to reproduce by changing the trigger from "timer"
> to "oneshot".
>
> Signed-off-by: Fabio Baltieri <fabio.baltieri@...il.com>
> Cc: Bryan Wu <bryan.wu@...onical.com>
> ---
>  drivers/leds/led-core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
> index 579eb78..3e9f934 100644
> --- a/drivers/leds/led-core.c
> +++ b/drivers/leds/led-core.c
> @@ -115,7 +115,8 @@ EXPORT_SYMBOL(led_blink_set_oneshot);
>  void led_brightness_set(struct led_classdev *led_cdev,
>                        enum led_brightness brightness)
>  {
> +       del_timer_sync(&led_cdev->blink_timer);

This is not necessary, since led_stop_software_blink() will call
del_timer_sync() as you want.

>        led_stop_software_blink(led_cdev);
> -       led_cdev->brightness_set(led_cdev, brightness);
> +       led_set_brightness(led_cdev, brightness);
>  }
>  EXPORT_SYMBOL(led_brightness_set);
> --
> 1.7.10.2.520.g6a4a482.dirty
>

Thanks,
-- 
Bryan Wu <bryan.wu@...onical.com>
Kernel Developer    +86.186-168-78255 Mobile
Canonical Ltd.      www.canonical.com
Ubuntu - Linux for human beings | www.ubuntu.com
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