[PATCH] pwm-backlight: allow for non-increasing brightness levels
From: Mike Dunn <hidden>
Date: 2013-09-12 18:37:08
Also in:
linux-devicetree, linux-pwm, lkml
Subsystem:
backlight class/subsystem, framebuffer layer, the rest · Maintainers:
Lee Jones, Daniel Thompson, Jingoo Han, Helge Deller, Linus Torvalds
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 max value, and instead searches the array for the max value and uses that as the normalizing value when determining the duty cycle. Signed-off-by: Mike Dunn <redacted> --- drivers/video/backlight/pwm_bl.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 1fea627..d66aaa0 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c@@ -27,6 +27,7 @@ struct pwm_bl_data { unsigned int period; unsigned int lth_brightness; unsigned int *levels; + unsigned int max_level; int (*notify)(struct device *, int brightness); void (*notify_after)(struct device *,
@@ -57,7 +58,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl) if (pb->levels) { duty_cycle = pb->levels[brightness]; - max = pb->levels[max]; + max = pb->levels[pb->max_level]; } else { duty_cycle = brightness; }
@@ -195,7 +196,15 @@ static int pwm_backlight_probe(struct platform_device *pdev) } if (data->levels) { - max = data->levels[data->max_brightness]; + int i, max_value = 0, max_idx = 0; + for (i = 0; i <= data->max_brightness; i++) { + if (data->levels[i] > max_value) { + max_value = data->levels[i]; + max_idx = i; + } + } + pb->max_level = max_idx; + max = data->levels[max_idx]; pb->levels = data->levels; } else max = data->max_brightness;
--
1.8.1.5