ACPI video: if no ACPI backlight support, use vendor drivers
authorThomas Renninger <trenn@suse.de>
Fri, 1 Aug 2008 15:37:55 +0000 (17:37 +0200)
committerLen Brown <len.brown@intel.com>
Sat, 8 Nov 2008 04:57:55 +0000 (23:57 -0500)
commitc3d6de698c84efdbdd3781b7058bcc339ab43da8
tree07e08d88bbaaef8a5a1dd58b9d19f7c860442d3a
parent22c13f9d8179f4c9caecfcb60a95214562b9addc
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>
Documentation/kernel-parameters.txt
drivers/acpi/Makefile
drivers/acpi/scan.c
drivers/acpi/video.c
drivers/acpi/video_detect.c [new file with mode: 0644]
include/linux/acpi.h