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authorHans de Goede <hdegoede@redhat.com>2014-02-13 16:32:51 +0100
committerJiri Slaby <jslaby@suse.cz>2014-03-05 17:13:47 +0100
commitc3fb946f7cabc1eb767b2c6ae42916b8fd358578 (patch)
tree8d314b5acdce01de775b7d30fb5b5a51bfa6d4e3
parentef0f10d829ab82b2a2cd8e2dca317027d2110237 (diff)
downloadlinux-linaro-stable-c3fb946f7cabc1eb767b2c6ae42916b8fd358578.tar.gz
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: Jiri Slaby <jslaby@suse.cz>
-rw-r--r--drivers/acpi/video.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index f193285968f8..5708e44376fe 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -729,6 +729,7 @@ 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 "
@@ -759,7 +760,12 @@ 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];