[Intel-gfx] [PATCH v2] drm/i915/opregion: ignore firmware requests for backlight change

[Rafael J. Wysocki]

On Monday, July 07, 2014 03:43:51 PM Aaron Lu 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.
> 
> 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>
> Acked-by: Jani Nikula <jani.nikula at intel.com>
> ---
> v2: add a debug message when ignoring opregion request as suggested by
>     Jani Nikula.
> 
>  drivers/acpi/video.c                  | 3 ++-
>  drivers/gpu/drm/i915/intel_opregion.c | 9 +++++++++
>  include/acpi/video.h                  | 2 ++
>  3 files changed, 13 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);

Is there any reason for this not to be EXPORT_SYMBOL_GPL()?

>  /* 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..4f6b53998d79 100644
> --- a/drivers/gpu/drm/i915/intel_opregion.c
> +++ b/drivers/gpu/drm/i915/intel_opregion.c
> @@ -403,6 +403,15 @@ 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()) {
> +		DRM_DEBUG_KMS("opregion backlight request ignored\n");
> +		return 0;
> +	}
> +
>  	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; }

And for this not to be static inline?

>  #endif
>  
>  #endif
> 

Rafael