The _DOD method lists which video output device is currently attached so we should only care about them and ignore others. An user recently reported that there are two acpi_video interfaces appeared on his system and one of them doesn't work. From the acpidump, it is found that there are more than one video output devices that have _BCM control method but the _DOD lists only one of them. So this patch checks if the video output device is in the _DOD list and will not create backlight device if it is not in the list. Also, we consider the broken _DOD case(reflected by the video->attached_count is 0) and do not change behaviour for those broken _DOD systems. Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=84111 Reported-and-tested-by: ntrrgc@xxxxxxxxx Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx> --- drivers/acpi/video.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c index 7285c7f9a935..807a88a0f394 100644 --- a/drivers/acpi/video.c +++ b/drivers/acpi/video.c @@ -1154,6 +1154,23 @@ acpi_video_device_bind(struct acpi_video_bus *video, } } +static bool acpi_video_device_in_dod(struct acpi_video_device *device) +{ + struct acpi_video_bus *video = device->video; + int i; + + /* If we have a broken _DOD, no need to test */ + if (!video->attached_count) + return true; + + for (i = 0; i < video->attached_count; i++) { + if (video->attached_array[i].bind_info == device) + return true; + } + + return false; +} + /* * Arg: * video : video bus device @@ -1593,6 +1610,15 @@ static void acpi_video_dev_register_backlight(struct acpi_video_device *device) static int count; char *name; + /* + * Do not create backlight device for video output + * device that is not in the enumerated list. + */ + if (!acpi_video_device_in_dod(device)) { + dev_dbg(&device->dev->dev, "not in _DOD list, ignore\n"); + return; + } + result = acpi_video_init_brightness(device); if (result) return; -- 1.9.3 -- 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
