Re: [RFC PATCH 12/40] drm/amd/display: add plane HDR multiplier driver-private property

[Harry Wentland]

On 4/23/23 10:10, Melissa Wen wrote:
> From: Joshua Ashton <joshua@xxxxxxxxx>
> 
> Multiplier to 'gain' the plane. When PQ is decoded using the fixed func
> transfer function to the internal FP16 fb, 1.0 -> 80 nits (on AMD at
> least) When sRGB is decoded, 1.0 -> 1.0.  Therefore, 1.0 multiplier = 80
> nits for SDR content. So if you want, 203 nits for SDR content, pass in
> (203.0 / 80.0).
> 

Is gamescope intending to use this?

Harry

> Co-developed-by: Melissa Wen <mwen@xxxxxxxxxx>
> Signed-off-by: Melissa Wen <mwen@xxxxxxxxxx>
> Signed-off-by: Joshua Ashton <joshua@xxxxxxxxx>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c   |  6 +++++
>  drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h      |  4 +++
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h | 12 +++++++++
>  .../amd/display/amdgpu_dm/amdgpu_dm_plane.c   | 25 ++++++++++++++-----
>  4 files changed, 41 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> index 24595906dab1..dd658f162f6f 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> @@ -1326,6 +1326,12 @@ amdgpu_display_create_color_properties(struct amdgpu_device *adev)
>  		return -ENOMEM;
>  	adev->mode_info.plane_degamma_tf_property = prop;
>  
> +	prop = drm_property_create_range(adev_to_drm(adev),
> +					 0, "AMD_PLANE_HDR_MULT", 0, UINT_MAX);
> +	if (!prop)
> +		return -ENOMEM;
> +	adev->mode_info.plane_hdr_mult_property = prop;
> +
>  	return 0;
>  }
>  #endif
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
> index ab9ce6f26c90..65a9d62ffbe4 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
> @@ -387,6 +387,10 @@ struct amdgpu_mode_info {
>  	 * linearize content with or without LUT.
>  	 */
>  	struct drm_property *plane_degamma_tf_property;
> +	/**
> +	 * @plane_hdr_mult_property:
> +	 */
> +	struct drm_property *plane_hdr_mult_property;
>  #endif
>  };
>  
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> index 005632c1c9ec..bb7307b9cfd5 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> @@ -51,6 +51,7 @@
>  
>  #define AMDGPU_DMUB_NOTIFICATION_MAX 5
>  
> +#define AMDGPU_HDR_MULT_DEFAULT (0x100000000LL)
>  /*
>  #include "include/amdgpu_dal_power_if.h"
>  #include "amdgpu_dm_irq.h"
> @@ -736,6 +737,17 @@ struct dm_plane_state {
>  	 * linearize.
>  	 */
>  	enum drm_transfer_function degamma_tf;
> +	/**
> +	 * @hdr_mult:
> +	 *
> +	 * Multiplier to 'gain' the plane.  When PQ is decoded using the fixed
> +	 * func transfer function to the internal FP16 fb, 1.0 -> 80 nits (on
> +	 * AMD at least). When sRGB is decoded, 1.0 -> 1.0, obviously.
> +	 * Therefore, 1.0 multiplier = 80 nits for SDR content.  So if you
> +	 * want, 203 nits for SDR content, pass in (203.0 / 80.0).  Format is
> +	 * S31.32 sign-magnitude.
> +	 */
> +	__u64 hdr_mult;
>  #endif
>  };
>  
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
> index 5b458cc0781c..57169dae8b3d 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
> @@ -1321,8 +1321,10 @@ static void dm_drm_plane_reset(struct drm_plane *plane)
>  		__drm_atomic_helper_plane_reset(plane, &amdgpu_state->base);
>  
>  #ifdef CONFIG_STEAM_DECK
> -	if (amdgpu_state)
> +	if (amdgpu_state) {
>  		amdgpu_state->degamma_tf = DRM_TRANSFER_FUNCTION_DEFAULT;
> +		amdgpu_state->hdr_mult = AMDGPU_HDR_MULT_DEFAULT;
> +	}
>  #endif
>  }
>  
> @@ -1424,11 +1426,11 @@ static void dm_drm_plane_destroy_state(struct drm_plane *plane,
>  #ifdef CONFIG_STEAM_DECK
>  int
>  amdgpu_dm_replace_property_blob_from_id(struct drm_device *dev,
> -					       struct drm_property_blob **blob,
> -					       uint64_t blob_id,
> -					       ssize_t expected_size,
> -					       ssize_t expected_elem_size,
> -					       bool *replaced)
> +					struct drm_property_blob **blob,
> +					uint64_t blob_id,
> +					ssize_t expected_size,
> +					ssize_t expected_elem_size,
> +					bool *replaced)
>  {
>  	struct drm_property_blob *new_blob = NULL;
>  
> @@ -1482,6 +1484,10 @@ dm_plane_attach_color_mgmt_properties(struct amdgpu_display_manager *dm,
>  					   dm->adev->mode_info.plane_degamma_tf_property,
>  					   DRM_TRANSFER_FUNCTION_DEFAULT);
>  	}
> +	/* HDR MULT is always available */
> +	drm_object_attach_property(&plane->base,
> +				   dm->adev->mode_info.plane_hdr_mult_property,
> +				   AMDGPU_HDR_MULT_DEFAULT);
>  }
>  
>  static int
> @@ -1507,6 +1513,11 @@ dm_atomic_plane_set_property(struct drm_plane *plane,
>  			dm_plane_state->degamma_tf = val;
>  			dm_plane_state->base.color_mgmt_changed = 1;
>  		}
> +	} else if (property == adev->mode_info.plane_hdr_mult_property) {
> +		if (dm_plane_state->hdr_mult != val) {
> +			dm_plane_state->hdr_mult = val;
> +			dm_plane_state->base.color_mgmt_changed = 1;
> +		}
>  	} else {
>  		drm_dbg_atomic(plane->dev,
>  			       "[PLANE:%d:%s] unknown property [PROP:%d:%s]]\n",
> @@ -1533,6 +1544,8 @@ dm_atomic_plane_get_property(struct drm_plane *plane,
>  			dm_plane_state->degamma_lut->base.id : 0;
>  	} else if (property == adev->mode_info.plane_degamma_tf_property) {
>  		*val = dm_plane_state->degamma_tf;
> +	} else if (property == adev->mode_info.plane_hdr_mult_property) {
> +		*val = dm_plane_state->hdr_mult;
>  	} else {
>  		return -EINVAL;
>  	}