From d440decb0576ba222f3ee1f435afe9d7d9144214 Mon Sep 17 00:00:00 2001 From: Mike Dunn Date: Sun, 22 Sep 2013 09:59:56 -0700 Subject: pwm-backlight: Allow for non-increasing brightness levels Currently the driver assumes that the values specified in the brightness-levels device tree property increase as they are parsed from left to right. But boards that invert the signal between the PWM output and the backlight will need to specify decreasing brightness-levels. This patch removes the assumption that the last element of the array is the maximum value, and instead searches the array for the maximum value and uses that in the duty cycle calculation. Signed-off-by: Mike Dunn Signed-off-by: Thierry Reding (cherry picked from commit 8f43e18e2769b3b28383903d501b4da29e388aad) --- drivers/video/backlight/pwm_bl.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-) (limited to 'drivers') diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index 60d489539b86..174ecdaebf1b 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -34,6 +34,7 @@ struct pwm_bl_data { struct regulator *power_supply; int enable_gpio; unsigned long enable_gpio_flags; + unsigned int scale; int (*notify)(struct device *, int brightness); void (*notify_after)(struct device *, @@ -42,23 +43,20 @@ struct pwm_bl_data { void (*exit)(struct device *); }; -static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness, - int max) +static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness) { + unsigned int lth = pb->lth_brightness; int duty_cycle, err; if (pb->enabled) return; - if (pb->levels) { + if (pb->levels) duty_cycle = pb->levels[brightness]; - max = pb->levels[max]; - } else { + else duty_cycle = brightness; - } - duty_cycle = (duty_cycle * (pb->period - pb->lth_brightness) / max) + - pb->lth_brightness; + duty_cycle = (duty_cycle * (pb->period - lth) / pb->scale) + lth; pwm_config(pb->pwm, duty_cycle, pb->period); @@ -100,7 +98,6 @@ static int pwm_backlight_update_status(struct backlight_device *bl) { struct pwm_bl_data *pb = bl_get_data(bl); int brightness = bl->props.brightness; - int max = bl->props.max_brightness; if (bl->props.power != FB_BLANK_UNBLANK || bl->props.fb_blank != FB_BLANK_UNBLANK || @@ -111,7 +108,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl) brightness = pb->notify(pb->dev, brightness); if (brightness > 0) - pwm_backlight_power_on(pb, brightness, max); + pwm_backlight_power_on(pb, brightness); else pwm_backlight_power_off(pb); @@ -218,7 +215,6 @@ static int pwm_backlight_probe(struct platform_device *pdev) struct backlight_properties props; struct backlight_device *bl; struct pwm_bl_data *pb; - unsigned int max; int ret; if (!data) { @@ -245,10 +241,15 @@ static int pwm_backlight_probe(struct platform_device *pdev) } if (data->levels) { - max = data->levels[data->max_brightness]; + unsigned int i; + + for (i = 0; i <= data->max_brightness; i++) + if (data->levels[i] > pb->scale) + pb->scale = data->levels[i]; + pb->levels = data->levels; } else - max = data->max_brightness; + pb->scale = data->max_brightness; pb->enable_gpio = data->enable_gpio; pb->enable_gpio_flags = data->enable_gpio_flags; @@ -304,7 +305,7 @@ static int pwm_backlight_probe(struct platform_device *pdev) pwm_set_period(pb->pwm, data->pwm_period_ns); pb->period = pwm_get_period(pb->pwm); - pb->lth_brightness = data->lth_brightness * (pb->period / max); + pb->lth_brightness = data->lth_brightness * (pb->period / pb->scale); memset(&props, 0, sizeof(struct backlight_properties)); props.type = BACKLIGHT_RAW; -- cgit v1.2.3