The pwm backlight should be powered off only in two cases: 1) pwm polarity is normal and brightness is zero. 2) pwm polarity is inversed and brightness is maximal, that is, 100% duty.
This patch implements this logic in the pwm backlight driver and actually fixes the issue that backlight is on when we intend to set the brightness to be zero for an inversed pwm signal. The root cause of the issue is that power is off in that case. Cc: Thierry Reding <[email protected]> Cc: Jingoo Han <[email protected]> Cc: Jean-Christophe Plagniol-Villard <[email protected]> Cc: Tomi Valkeinen <[email protected]> Signed-off-by: Liu Ying <[email protected]> --- drivers/video/backlight/pwm_bl.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index b75201f..e61e66a 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -100,6 +100,8 @@ static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness) static int pwm_backlight_update_status(struct backlight_device *bl) { struct pwm_bl_data *pb = bl_get_data(bl); + enum pwm_polarity polarity = pb->pwm->polarity; + int max = bl->props.max_brightness; int brightness = bl->props.brightness; int duty_cycle; @@ -111,12 +113,14 @@ static int pwm_backlight_update_status(struct backlight_device *bl) if (pb->notify) brightness = pb->notify(pb->dev, brightness); - if (brightness > 0) { + if ((polarity == PWM_POLARITY_NORMAL && brightness == 0) || + (polarity == PWM_POLARITY_INVERSED && brightness == max)) { + pwm_backlight_power_off(pb); + } else { duty_cycle = compute_duty_cycle(pb, brightness); pwm_config(pb->pwm, duty_cycle, pb->period); pwm_backlight_power_on(pb, brightness); - } else - pwm_backlight_power_off(pb); + } if (pb->notify_after) pb->notify_after(pb->dev, brightness); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-pwm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
