Re: [PATCHv3] pwm_backlight: pass correct brightness to callback

From: Thierry Reding
Date: Mon Jul 09 2012 - 02:30:08 EST


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@xxxxxxxxxx>
> ---
> 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
>
>
>

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