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backlight: Do not clamp brightness for LEDs

Browse Source 
https://bugs.freedesktop.org/show_bug.cgi?id=77092

On Thu, Jun 05, 2014 at 08:37:20AM +0200, Lennart Poettering wrote:
> The patch is line-broken, please send an uncorrupted patch!
I am very sorry, I forgot that my client limits line width. I will use
mutt now on.
> clamp_brightness() clamps the brightness value to the range of the
> actual device. This is a recent addition that was added to deal with
> driver updates where the resolution is changed. I don't think this part
> should be dropped for LED devices. The clamp_brightness() call hence
> should be called unconditionally, however, internally it should use a
> different min_brightness value if something is an !backlight devices...
Thank you for explanation, this sounds very reasonable to me. Please,
see updated patch:
This commit is contained in:
Denis Tikhomirov 2014-06-05 23:59:40 +04:00 committed by Lennart Poettering
parent 51cb9d734a
commit 4cd2b2cf8c
Notes: Lennart Poettering 2014-06-11 13:11:09 +02:00 
Backport: bugfix
1 changed files with 10 additions and 3 deletions
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13
src/backlight/backlight.c
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@ -225,11 +225,13 @@ static unsigned get_max_brightness(struct udev_device *device) {
/* Some systems turn the backlight all the way off at the lowest levels.
* clamp_brightness clamps the saved brightness to at least 1 or 5% of
* max_brightness. This avoids preserving an unreadably dim screen, which
* would otherwise force the user to disable state restoration. */
* max_brightness in case of 'backlight' subsystem. This avoids preserving
* an unreadably dim screen, which would otherwise force the user to
* disable state restoration. */
static void clamp_brightness(struct udev_device *device, char **value, unsigned max_brightness) {
int r;
unsigned brightness, new_brightness, min_brightness;
const char *subsystem;
r = safe_atou(*value, &brightness);
if (r < 0) {
@ -237,7 +239,12 @@ static void clamp_brightness(struct udev_device *device, char **value, unsigned
return;
}
min_brightness = MAX(1U, max_brightness/20);
subsystem = udev_device_get_subsystem(device);
if (streq_ptr(subsystem, "backlight"))
min_brightness = MAX(1U, max_brightness/20);
else
min_brightness = 0;
new_brightness = CLAMP(brightness, min_brightness, max_brightness);
if (new_brightness != brightness) {
char *old_value = *value;