ACPI video: if no ACPI backlight support, use vendor drivers

If an ACPI graphics device supports backlight brightness functions (cmp. with
latest ACPI spec Appendix B), let the ACPI video driver control backlight and
switch backlight control off in vendor specific ACPI drivers (asus_acpi,
thinkpad_acpi, eeepc, fujitsu_laptop, msi_laptop, sony_laptop, acer-wmi).

Currently it is possible to load above drivers and let both poke on the
brightness HW registers, the video and vendor specific ACPI drivers -> bad.

This patch provides the basic support to check for BIOS capabilities before
driver loading time. Driver specific modifications are in separate follow up
patches.

"acpi_backlight=vendor"
	Prever vendor driver over ACPI driver for backlight.
"acpi_backlight=video" (default)
	Prever ACPI driver over vendor driver for backlight.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Thomas Renninger 2008-08-01 17:37:55 +02:00 committed by Len Brown
parent 22c13f9d81
commit c3d6de698c
6 changed files with 345 additions and 43 deletions

View file

@ -198,6 +198,18 @@ and is between 256 and 4096 characters. It is defined in the file
that require a timer override, but don't have
HPET
acpi_backlight= [HW,ACPI]
acpi_backlight=vendor
acpi_backlight=video
If set to vendor, prefer vendor specific driver
(e.g. thinkpad_acpi, sony_acpi, etc.) instead
of the ACPI video.ko driver.
acpi_display_output= [HW,ACPI]
acpi_display_output=vendor
acpi_display_output=video
See above.
acpi.debug_layer= [HW,ACPI]
Format: <int>
Each bit of the <int> indicates an ACPI debug layer,