On 09/20/2013 04:36 PM, Jani Nikula wrote:
> On Tue, 17 Sep 2013, Aaron Lu <aaron.lu@xxxxxxxxx> 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.
>>
>> This patch is an evolution from previous work done by Matthew Garrett,
>> Chun-Yi Lee, Seth Forshee and Rafael J. Wysocki.
>>
>> Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx>
>> ---
>> drivers/acpi/internal.h | 5 ++---
>> drivers/acpi/video.c | 27 +++++----------------------
>> drivers/acpi/video_detect.c | 14 ++++++++++++--
>> 3 files changed, 19 insertions(+), 27 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 5ad5a71..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;
>> @@ -1677,23 +1677,6 @@ static int acpi_video_bus_unregister_backlight(struct acpi_video_bus *video)
>> return error;
>> }
>>
>> -int acpi_video_unregister_backlight(void)
>> -{
>> - struct acpi_video_bus *video;
>> - int error = 0;
>> -
>> - mutex_lock(&video_list_lock);
>> - list_for_each_entry(video, &video_bus_head, entry) {
>> - error = acpi_video_bus_unregister_backlight(video);
>> - if (error)
>> - break;
>> - }
>> - mutex_unlock(&video_list_lock);
>> -
>> - return error;
>> -}
>> -EXPORT_SYMBOL(acpi_video_unregister_backlight);
>
> You add this in patch 2/3 only to remove it again in 3/3?
This is a mistake while I'm preparing the patches, I'll fix it in next
revision, thanks for pointing this out.
>
>> -
>> static void acpi_video_dev_add_notify_handler(struct acpi_video_device *device)
>> {
>> acpi_status status;
>> 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;
>> + return acpi_video_backlight_support();
>> +}
>
> IIUC this expects the raw backlight device to have been registered prior
> to calling acpi_video_register(). This only works for i915 which calls
> acpi_video_register() itself.
Yes. Since all problematic laptops reported till now are intel graphics
card based, I didn't cover other cases.
Thanks,
Aaron
>
>
> BR,
> Jani.
>
>
>
>> +EXPORT_SYMBOL(acpi_video_verify_backlight_support);
>> +
>> /*
>> * Use acpi_backlight=vendor/video to force that backlight switching
>> * is processed by vendor specific acpi drivers or video.ko driver.
>> --
>> 1.8.4.12.g2ea3df6
>>
>
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