If too high a brightness value has been saved (e.g. due to kernel mechanism changing from one kernel version to another, or booting the userspace on another system), the brightness update fails and the process exits.
Clamp saved brightness between the policy minimum introduced in commit 7b909d7407965c03caaba30daae7aee113627a83 Author: Josh Triplett <[email protected]> Date: Tue Mar 11 21:16:33 2014 -0700 backlight: Avoid restoring brightness to an unreadably dim level and the absolute maximum. --- UNCOMPILED AND UNTESTED; please consider this more a bug report than a real contribution... Based on reading the source while debugging https://bugs.freedesktop.org/show_bug.cgi?id=78200 --- src/backlight/backlight.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/src/backlight/backlight.c b/src/backlight/backlight.c index c708391612a2..d48a73e69364 100644 --- a/src/backlight/backlight.c +++ b/src/backlight/backlight.c @@ -229,7 +229,7 @@ static unsigned get_max_brightness(struct udev_device *device) { * 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; + unsigned brightness, new_brightness, min_brightness; r = safe_atou(*value, &brightness); if (r < 0) { @@ -237,7 +237,8 @@ static void clamp_brightness(struct udev_device *device, char **value, unsigned return; } - new_brightness = MAX3(brightness, 1U, max_brightness/20); + min_brightness = MAX(1U, max_brightness/20); + new_brightness = CLAMP(brightness, min_brightness, max_brightness); if (new_brightness != brightness) { char *old_value = *value; @@ -247,7 +248,11 @@ static void clamp_brightness(struct udev_device *device, char **value, unsigned return; } - log_debug("Saved brightness %s too low; increasing to %s.", old_value, *value); + log_debug("Saved brightness %s %s to %s.", old_value, + new_brightness < min_brightness ? + "too low; increasing" : "too high; decreasing", + *value); + free(old_value); } } -- 1.9.1 _______________________________________________ systemd-devel mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/systemd-devel
