In case of an empty 'brightness-levels' array in the device tree or
a non empty one but containing only zeros the value of
'pwm_backlight->scale' would remain 0 possibly causing a division by zero
in the function compute_duty_cycle().
To fix it we check the computed value in case we actually have a 'brightness-levels'
array in the device tree otherwise we implicitly assume a simple array
of the form { 0, 1, 2, ..., 100 } and set the scale to 100.
---
drivers/video/backlight-pwm.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)
diff --git a/drivers/video/backlight-pwm.c b/drivers/video/backlight-pwm.c
index 5ff40a9..7f1715d 100644
--- a/drivers/video/backlight-pwm.c
+++ b/drivers/video/backlight-pwm.c
@@ -128,6 +128,13 @@ static int pwm_backlight_parse_dt(struct device_d *dev,
if (!node)
return -ENODEV;
+ ret = of_property_read_u32(node, "default-brightness-level",
+ &value);
+ if (ret < 0)
+ return ret;
+
+ pwm_backlight->backlight.brightness_default = value;
+
/* determine the number of brightness levels */
prop = of_find_property(node, "brightness-levels", &length);
if (!prop)
@@ -153,14 +160,13 @@ static int pwm_backlight_parse_dt(struct device_d *dev,
if (pwm_backlight->levels[i] > pwm_backlight->scale)
pwm_backlight->scale = pwm_backlight->levels[i];
- ret = of_property_read_u32(node, "default-brightness-level",
- &value);
- if (ret < 0)
- return ret;
-
- pwm_backlight->backlight.brightness_default = value;
- pwm_backlight->backlight.brightness_max = pwm_backlight->scale;
+ if (pwm_backlight->scale == 0)
+ return -EINVAL;
+ } else {
+ /* We implicitly assume here a linear levels array { 0, 1, 2, ... 100 } */
+ pwm_backlight->scale = 100;
}
+ pwm_backlight->backlight.brightness_max = pwm_backlight->scale;
pwm_backlight->enable_gpio = of_get_named_gpio_flags(node, "enable-gpios", 0, &flags);
--
2.9.1
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