On Thursday, October 10, 2013 09:02:55 AM Aaron Lu wrote:
On 10/10/2013 08:29 AM, Rafael J. Wysocki wrote:
On Tuesday, October 08, 2013 02:40:00 PM Aaron Lu wrote:
According to Matthew Garrett, "Windows 8 leaves backlight control up to individual graphics drivers rather than making ACPI calls itself. There's plenty of evidence to suggest that the Intel driver for Windows [8] doesn't use the ACPI interface, including the fact that it's broken on a bunch of machines when the OS claims to support Windows 8. The simplest thing to do appears to be to disable the ACPI backlight interface on these systems".
So for Win8 systems, if there is native backlight control interface registered by GPU driver, ACPI video will not register its own. For users who prefer to keep ACPI video's backlight interface, the existing kernel cmdline option acpi_backlight=video can be used.
Signed-off-by: Aaron Lu aaron.lu@intel.com Tested-by: Igor Gnatenko i.gnatenko.brain@gmail.com Tested-by: Yves-Alexis Perez corsac@debian.org Tested-by: Mika Westerberg mika.westerberg@linux.intel.com
drivers/acpi/internal.h | 5 ++--- drivers/acpi/video.c | 10 +++++----- drivers/acpi/video_detect.c | 14 ++++++++++++-- 3 files changed, 19 insertions(+), 10 deletions(-)
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h index 20f4233..453ae8d 100644 --- a/drivers/acpi/internal.h +++ b/drivers/acpi/internal.h @@ -169,9 +169,8 @@ int acpi_create_platform_device(struct acpi_device *adev, Video -------------------------------------------------------------------------- */ #if defined(CONFIG_ACPI_VIDEO) || defined(CONFIG_ACPI_VIDEO_MODULE) -bool acpi_video_backlight_quirks(void); -#else -static inline bool acpi_video_backlight_quirks(void) { return false; } +bool acpi_osi_is_win8(void); +bool acpi_video_verify_backlight_support(void); #endif
#endif /* _ACPI_INTERNAL_H_ */ diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c index 3bd1eaa..343db59 100644 --- a/drivers/acpi/video.c +++ b/drivers/acpi/video.c @@ -1256,8 +1256,8 @@ acpi_video_switch_brightness(struct acpi_video_device *device, int event) unsigned long long level_current, level_next; int result = -EINVAL;
- /* no warning message if acpi_backlight=vendor is used */
- if (!acpi_video_backlight_support())
/* no warning message if acpi_backlight=vendor or a quirk is used */
if (!acpi_video_verify_backlight_support()) return 0;
if (!device->brightness)
@@ -1386,13 +1386,13 @@ acpi_video_bus_get_devices(struct acpi_video_bus *video, static int acpi_video_bus_start_devices(struct acpi_video_bus *video) { return acpi_video_bus_DOS(video, 0,
acpi_video_backlight_quirks() ? 1 : 0);
acpi_osi_is_win8() ? 1 : 0);}
static int acpi_video_bus_stop_devices(struct acpi_video_bus *video) { return acpi_video_bus_DOS(video, 0,
acpi_video_backlight_quirks() ? 0 : 1);
acpi_osi_is_win8() ? 0 : 1);}
static void acpi_video_bus_notify(struct acpi_device *device, u32 event) @@ -1558,7 +1558,7 @@ acpi_video_bus_match(acpi_handle handle, u32 level, void *context,
static void acpi_video_dev_register_backlight(struct acpi_video_device *device) {
- if (acpi_video_backlight_support()) {
- if (acpi_video_verify_backlight_support()) { struct backlight_properties props; struct pci_dev *pdev; acpi_handle acpi_parent;
diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c index 940edbf..23d7d26 100644 --- a/drivers/acpi/video_detect.c +++ b/drivers/acpi/video_detect.c @@ -37,6 +37,7 @@ #include <linux/acpi.h> #include <linux/dmi.h> #include <linux/pci.h> +#include <linux/backlight.h>
#include "internal.h"
@@ -233,11 +234,11 @@ static void acpi_video_caps_check(void) acpi_video_get_capabilities(NULL); }
-bool acpi_video_backlight_quirks(void) +bool acpi_osi_is_win8(void) { return acpi_gbl_osi_data >= ACPI_OSI_WIN_8; } -EXPORT_SYMBOL(acpi_video_backlight_quirks); +EXPORT_SYMBOL(acpi_osi_is_win8);
/* Promote the vendor interface instead of the generic video module.
- This function allow DMI blacklists to be implemented by externals
@@ -283,6 +284,15 @@ int acpi_video_backlight_support(void) } EXPORT_SYMBOL(acpi_video_backlight_support);
+bool acpi_video_verify_backlight_support(void) +{
- if (!(acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO) &&
acpi_osi_is_win8() && backlight_device_registered(BACKLIGHT_RAW))return false;If I'm not mistaken, this will introduce a regression for the people who have problems with the native i915 backlight on Win8-compatible systems. I'd prefer to avoid that at this point.
OK, I see.
Then I'm afraid a new kernel command line option is needed, something like video.use_native_backlight and set it to false by default, then for people who need to avoid the ACPI video backlight interface, they can add video.use_native_backlight=true to kernel cmdline.
One thing I need to mention is, with the new cmdline option, users will need to manually add a kernel cmdline option to make backlight work on their systems, while they can already make backlight work by modifying xorg.conf to specify using intel_backlight interface, so it doesn't seem this patchset will be very useful then...
Except if we add a (black)list of systems where that option will be 'true' by default instead of the _OSI blacklist we have today.
Also we can switch the default during development cycles to get an idea about how many systems are affected and maybe we can find a way to fix them, in which case we can simply drop the option.
Thanks, Rafael