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| author | Lucas Stach <l.stach@pengutronix.de> | 2018-06-20 11:47:49 +0200 |
|---|---|---|
| committer | Sascha Hauer <s.hauer@pengutronix.de> | 2018-06-21 12:57:13 +0200 |
| commit | 898ec202d06ccf89506b9f64bea438a1974b4687 (patch) | |
| tree | 886a5b17d1072579232be47e0304005aa618f1a5 | |
| parent | be940f1a513b5167963174eca1d9509aaddda2fe (diff) | |
| download | barebox-898ec202d06ccf89506b9f64bea438a1974b4687.tar.gz barebox-898ec202d06ccf89506b9f64bea438a1974b4687.tar.xz | |
video: backlight: add slew time parameter
Currently the backlight implementation stretches a brightness change over
a period of 100ms. While this is a fine default for PWM backlights, a user
might wish to change this slew time to meet other constraints or even
completely disable it for some backlight devices.
Add a parameter and provide the default value from the backlight device.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
| -rw-r--r-- | drivers/video/backlight-pwm.c | 1 | ||||
| -rw-r--r-- | drivers/video/backlight.c | 14 | ||||
| -rw-r--r-- | include/video/backlight.h | 1 |
3 files changed, 14 insertions, 2 deletions
diff --git a/drivers/video/backlight-pwm.c b/drivers/video/backlight-pwm.c index ec35bd1bc0..997235a74a 100644 --- a/drivers/video/backlight-pwm.c +++ b/drivers/video/backlight-pwm.c @@ -206,6 +206,7 @@ static int backlight_pwm_of_probe(struct device_d *dev) pwm_backlight->period = pwm_get_period(pwm_backlight->pwm); + pwm_backlight->backlight.slew_time_ms = 100; pwm_backlight->backlight.brightness_set = backlight_pwm_set; pwm_backlight->backlight.node = dev->device_node; diff --git a/drivers/video/backlight.c b/drivers/video/backlight.c index 09c0e47af6..30d52fcb68 100644 --- a/drivers/video/backlight.c +++ b/drivers/video/backlight.c @@ -15,6 +15,15 @@ int backlight_set_brightness(struct backlight_device *bl, int brightness) if (brightness == bl->brightness_cur) return 0; + if (!bl->slew_time_ms) { + ret = bl->brightness_set(bl, brightness); + if (ret) + return ret; + + bl->brightness_cur = bl->brightness = brightness; + return 0; + } + if (brightness > bl->brightness_cur) step = 1; else @@ -34,10 +43,9 @@ int backlight_set_brightness(struct backlight_device *bl, int brightness) if (i == brightness) break; - udelay(100000 / num_steps); + udelay(bl->slew_time_ms * 1000 / num_steps); } - bl->brightness_cur = bl->brightness = brightness; return ret; @@ -72,6 +80,8 @@ int backlight_register(struct backlight_device *bl) dev_add_param_uint32(&bl->dev, "brightness", backlight_brightness_set, NULL, &bl->brightness, "%d", bl); + dev_add_param_uint32(&bl->dev, "slew_time_ms", NULL, NULL, + &bl->slew_time_ms, "%d", NULL); list_add_tail(&bl->list, &backlights); diff --git a/include/video/backlight.h b/include/video/backlight.h index 8dc49dc113..afa384cc9a 100644 --- a/include/video/backlight.h +++ b/include/video/backlight.h @@ -7,6 +7,7 @@ struct backlight_device { int brightness_cur; int brightness_max; int brightness_default; + int slew_time_ms; /* time to stretch brightness changes */ int (*brightness_set)(struct backlight_device *, int brightness); struct list_head list; struct device_d dev; |