From c3d6de698c84efdbdd3781b7058bcc339ab43da8 Mon Sep 17 00:00:00 2001 From: Thomas Renninger Date: Fri, 1 Aug 2008 17:37:55 +0200 Subject: 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 Acked-by: Zhang Rui Signed-off-by: Andi Kleen Signed-off-by: Len Brown --- Documentation/kernel-parameters.txt | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index c86c0745971..dd5013f974d 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -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: Each bit of the indicates an ACPI debug layer, -- cgit v1.2.3-70-g09d2