From: Zhang Rui <rui.zhang@xxxxxxxxx> This fixes a regression in 3.4-rc1 caused by commit ea9f8856bd6d4ed45885b06a338f7362cd6c60e5 (ACPI video: Harden video bus adding.) Some platforms don't have _DOS control method, but the ACPI backlight still works. We should not invoke _DOS for these platforms. https://bugzilla.kernel.org/show_bug.cgi?id=43168 Cc: Igor Murzov <intergalactic.anonymous@xxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx> Signed-off-by: Len Brown <len.brown@xxxxxxxxx> --- drivers/acpi/video.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c index 9577b6f..4134b30 100644 --- a/drivers/acpi/video.c +++ b/drivers/acpi/video.c @@ -558,6 +558,8 @@ acpi_video_bus_DOS(struct acpi_video_bus *video, int bios_flag, int lcd_flag) union acpi_object arg0 = { ACPI_TYPE_INTEGER }; struct acpi_object_list args = { 1, &arg0 }; + if (!video->cap._DOS) + return 0; if (bios_flag < 0 || bios_flag > 3 || lcd_flag < 0 || lcd_flag > 1) return -EINVAL; -- 1.7.11.1.104.ge7b44f1
