From: Zhao Yakui <yakui.zhao@xxxxxxxxx> upstream commmit: c2c789057f075022658b38b498755c29c1ba8055 According to acpi spec , the objectes of _BCL and _BCM are required if integrated LCD is present and supports brightness level and the _BQC is the optional object. So the _BQC object will be ignored when the backlight device is registered. At the same time when there is no _BQC object, the current brightness will be set to the maximum. http://bugzilla.kernel.org/show_bug.cgi?id=10206 Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx> Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx> Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx> --- drivers/acpi/video.c | 14 ++++++++++++-- 1 files changed, 12 insertions(+), 2 deletions(-) Index: linux-2.6.26.y/drivers/acpi/video.c =================================================================== --- linux-2.6.26.y.orig/drivers/acpi/video.c +++ linux-2.6.26.y/drivers/acpi/video.c @@ -720,7 +720,7 @@ static void acpi_video_device_find_cap(s kfree(obj); - if (device->cap._BCL && device->cap._BCM && device->cap._BQC && max_level > 0){ + if (device->cap._BCL && device->cap._BCM && max_level > 0) { int result; static int count = 0; char *name; @@ -732,7 +732,17 @@ static void acpi_video_device_find_cap(s device->backlight = backlight_device_register(name, NULL, device, &acpi_backlight_ops); device->backlight->props.max_brightness = device->brightness->count-3; - device->backlight->props.brightness = acpi_video_get_brightness(device->backlight); + /* + * If there exists the _BQC object, the _BQC object will be + * called to get the current backlight brightness. Otherwise + * the brightness will be set to the maximum. + */ + if (device->cap._BQC) + device->backlight->props.brightness = + acpi_video_get_brightness(device->backlight); + else + device->backlight->props.brightness = + device->backlight->props.max_brightness; backlight_update_status(device->backlight); kfree(name); -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
