diff mbox

[PATCHv3] pwm_backlight: pass correct brightness to callback

Message ID 1341813863-18822-1-git-send-email-acourbot@nvidia.com (mailing list archive)
State New, archived
Headers show

Commit Message

Alexandre Courbot July 9, 2012, 6:04 a.m. UTC
pwm_backlight_update_status calls the notify() and notify_after()
callbacks before and after applying the new PWM settings. However, if
brightness levels are used, the brightness value will be changed from
the index into the levels array to the PWM duty cycle length before
being passed to notify_after(), which results in inconsistent behavior.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
 drivers/video/backlight/pwm_bl.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

Comments

Thierry Reding July 9, 2012, 6:30 a.m. UTC | #1
On Mon, Jul 09, 2012 at 03:04:23PM +0900, Alexandre Courbot wrote:
> pwm_backlight_update_status calls the notify() and notify_after()
> callbacks before and after applying the new PWM settings. However, if
> brightness levels are used, the brightness value will be changed from
> the index into the levels array to the PWM duty cycle length before
> being passed to notify_after(), which results in inconsistent behavior.
> 
> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
> ---
>  drivers/video/backlight/pwm_bl.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)

Applied, with a minor stylistic fixup adding a blank line after the
duty_cycle variable declaration. Thanks.

Thierry

> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
> index 057389d..be48517 100644
> --- a/drivers/video/backlight/pwm_bl.c
> +++ b/drivers/video/backlight/pwm_bl.c
> @@ -54,14 +54,17 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
>  		pwm_config(pb->pwm, 0, pb->period);
>  		pwm_disable(pb->pwm);
>  	} else {
> +		int duty_cycle;
>  		if (pb->levels) {
> -			brightness = pb->levels[brightness];
> +			duty_cycle = pb->levels[brightness];
>  			max = pb->levels[max];
> +		} else {
> +			duty_cycle = brightness;
>  		}
>  
> -		brightness = pb->lth_brightness +
> -			(brightness * (pb->period - pb->lth_brightness) / max);
> -		pwm_config(pb->pwm, brightness, pb->period);
> +		duty_cycle = pb->lth_brightness +
> +		     (duty_cycle * (pb->period - pb->lth_brightness) / max);
> +		pwm_config(pb->pwm, duty_cycle, pb->period);
>  		pwm_enable(pb->pwm);
>  	}
>  
> -- 
> 1.7.11.1
> 
> 
>
diff mbox

Patch

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 057389d..be48517 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -54,14 +54,17 @@  static int pwm_backlight_update_status(struct backlight_device *bl)
 		pwm_config(pb->pwm, 0, pb->period);
 		pwm_disable(pb->pwm);
 	} else {
+		int duty_cycle;
 		if (pb->levels) {
-			brightness = pb->levels[brightness];
+			duty_cycle = pb->levels[brightness];
 			max = pb->levels[max];
+		} else {
+			duty_cycle = brightness;
 		}
 
-		brightness = pb->lth_brightness +
-			(brightness * (pb->period - pb->lth_brightness) / max);
-		pwm_config(pb->pwm, brightness, pb->period);
+		duty_cycle = pb->lth_brightness +
+		     (duty_cycle * (pb->period - pb->lth_brightness) / max);
+		pwm_config(pb->pwm, duty_cycle, pb->period);
 		pwm_enable(pb->pwm);
 	}