From 67002cbc9aba1b05576f3390410a84775dd060f2 Mon Sep 17 00:00:00 2001 From: Denis Tikhomirov Date: Thu, 5 Jun 2014 23:59:40 +0400 Subject: [PATCH] backlight: Do not clamp brightness for LEDs 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: (cherry picked from commit 4cd2b2cf8ca585d15ebc859701b346658262b5bb) (cherry picked from commit 385d2ab37b1a00b513edf5c3888b91d91ad3aae3) --- src/backlight/backlight.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/src/backlight/backlight.c b/src/backlight/backlight.c index 77ae48c..e944f57 100644 --- a/src/backlight/backlight.c +++ b/src/backlight/backlight.c @@ -221,11 +221,13 @@ 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) { @@ -233,7 +235,12 @@ 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;