@@ -656,6 +656,7 @@ acpi_video_init_brightness(struct acpi_video_device *device)
union acpi_object *o;
struct acpi_video_device_brightness *br = NULL;
int result = -EINVAL;
+ u32 value;
if (!ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device, &obj))) {
ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available "
@@ -686,7 +687,12 @@ acpi_video_init_brightness(struct acpi_video_device *device)
printk(KERN_ERR PREFIX "Invalid data\n");
continue;
}
- br->levels[count] = (u32) o->integer.value;
+ value = (u32) o->integer.value;
+ /* Skip duplicate entries */
+ if (count > 2 && br->levels[count - 1] == value)
+ continue;
+
+ br->levels[count] = value;
if (br->levels[count] > max_level)
max_level = br->levels[count];
This is a note to let you know that I have just added a patch titled ACPI / video: Filter the _BCL table for duplicate brightness values to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.20. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 259e6d8c076ac92db561957d7d57b6c8c3a51f92 Mon Sep 17 00:00:00 2001 From: Hans de Goede <hdegoede@redhat.com> Date: Thu, 13 Feb 2014 16:32:51 +0100 Subject: ACPI / video: Filter the _BCL table for duplicate brightness values commit bd8ba20597f0cfef3ef65c3fd2aa92ab23d4c8e1 upstream. Some devices have duplicate entries in there brightness levels table, ie on my Dell Latitude E6430 the table looks like this: [ 3.686060] acpi backlight index 0, val 80 [ 3.686095] acpi backlight index 1, val 50 [ 3.686122] acpi backlight index 2, val 5 [ 3.686147] acpi backlight index 3, val 5 [ 3.686172] acpi backlight index 4, val 5 [ 3.686197] acpi backlight index 5, val 5 [ 3.686223] acpi backlight index 6, val 5 [ 3.686248] acpi backlight index 7, val 5 [ 3.686273] acpi backlight index 8, val 6 [ 3.686332] acpi backlight index 9, val 7 [ 3.686356] acpi backlight index 10, val 8 [ 3.686380] acpi backlight index 11, val 9 etc. Notice that brightness values 0-5 are all mapped to 5. This means that if userspace writes any value between 0 and 5 to the brightness sysfs attribute and then reads it, it will always return 0, which is somewhat unexpected. This is a problem for ie gnome-settings-daemon, which uses read-modify-write logic when the users presses the brightness up or down keys. This is done this way to take brightness changes from other sources into account. On this specific laptop what happens once the brightness has been set to 0, is that gsd reads 0, adds 5, writes 5, and on the next brightness up key press again reads 0, so things get stuck at the lowest brightness setting. Filtering out the duplicate table entries, makes any write to brightness read back as the written value as one would expect, fixing this. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/acpi/video.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) -- 1.8.3.2