[Intel-gfx] [PATCH] drm/i915/opregion: ignore firmware requests for backlight change

[Aaron Lu]

On 06/25/2014 07:08 PM, Jani Nikula wrote:
> On Tue, 24 Jun 2014, Aaron Lu <aaron.lu at intel.com> wrote:
>> Some Thinkpad laptops' firmware will initiate a backlight level change
>> request through operation region on the events of AC plug/unplug, but
>> since we are not using firmware's interface to do the backlight setting
>> on these affected laptops, we do not want the firmware to use some
>> arbitrary value from its ASL variable to set the backlight level on
>> AC plug/unplug either.
> 
> I'm curious whether this happens with EFI boot, or only with legacy.

Igor, Anton,

Are you using legacy boot or UEFI boot?
Possible to test the other case?

> 
> One comment inline, otherwise

Will add that in next revision.

> 
> Acked-by: Jani Nikula <jani.nikula at intel.com>

Thanks for the review!

-Aaron

> 
> for merging through the ACPI tree, as the change is more likely to
> conflict there.
> 
>> Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=76491
>> Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=77091
>> Reported-and-tested-by: Igor Gnatenko <i.gnatenko.brain at gmail.com>
>> Reported-and-tested-by: Anton Gubarkov <anton.gubarkov at gmail.com>
>> Signed-off-by: Aaron Lu <aaron.lu at intel.com>
>> ---
>>  drivers/acpi/video.c                  | 3 ++-
>>  drivers/gpu/drm/i915/intel_opregion.c | 7 +++++++
>>  include/acpi/video.h                  | 2 ++
>>  3 files changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
>> index fb9ffe9adc64..cf99d6d2d491 100644
>> --- a/drivers/acpi/video.c
>> +++ b/drivers/acpi/video.c
>> @@ -241,13 +241,14 @@ static bool acpi_video_use_native_backlight(void)
>>  		return use_native_backlight_dmi;
>>  }
>>  
>> -static bool acpi_video_verify_backlight_support(void)
>> +bool acpi_video_verify_backlight_support(void)
>>  {
>>  	if (acpi_osi_is_win8() && acpi_video_use_native_backlight() &&
>>  	    backlight_device_registered(BACKLIGHT_RAW))
>>  		return false;
>>  	return acpi_video_backlight_support();
>>  }
>> +EXPORT_SYMBOL(acpi_video_verify_backlight_support);
>>  
>>  /* backlight device sysfs support */
>>  static int acpi_video_get_brightness(struct backlight_device *bd)
>> diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
>> index 2e2c71fcc9ed..02943d93e88e 100644
>> --- a/drivers/gpu/drm/i915/intel_opregion.c
>> +++ b/drivers/gpu/drm/i915/intel_opregion.c
>> @@ -403,6 +403,13 @@ static u32 asle_set_backlight(struct drm_device *dev, u32 bclp)
>>  
>>  	DRM_DEBUG_DRIVER("bclp = 0x%08x\n", bclp);
>>  
>> +	/*
>> +	 * If the acpi_video interface is not supposed to be used, don't
>> +	 * bother processing backlight level change requests from firmware.
>> +	 */
>> +	if (!acpi_video_verify_backlight_support())
>> +		return 0;
> 
> I'd appreciate a DRM_DEBUG_KMS here about what happened. We're bound to
> wonder about that staring at some dmesg later on!
> 
>> +
>>  	if (!(bclp & ASLE_BCLP_VALID))
>>  		return ASLC_BACKLIGHT_FAILED;
>>  
>> diff --git a/include/acpi/video.h b/include/acpi/video.h
>> index ea4c7bbded4d..92f8c4bffefb 100644
>> --- a/include/acpi/video.h
>> +++ b/include/acpi/video.h
>> @@ -22,6 +22,7 @@ extern void acpi_video_unregister(void);
>>  extern void acpi_video_unregister_backlight(void);
>>  extern int acpi_video_get_edid(struct acpi_device *device, int type,
>>  			       int device_id, void **edid);
>> +extern bool acpi_video_verify_backlight_support(void);
>>  #else
>>  static inline int acpi_video_register(void) { return 0; }
>>  static inline void acpi_video_unregister(void) { return; }
>> @@ -31,6 +32,7 @@ static inline int acpi_video_get_edid(struct acpi_device *device, int type,
>>  {
>>  	return -ENODEV;
>>  }
>> +static bool acpi_video_verify_backlight_support() { return false; }
>>  #endif
>>  
>>  #endif
>> -- 
>> 1.9.3
>>
>