On Thu, 10 Aug 2023 15:02:49 -0100
Melissa Wen <m...@igalia.com> wrote:

> From: Joshua Ashton <jos...@froggi.es>
> 
> 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).

Does this mean that the fixed-function PQ EOTF is
actually [0, 128] -> [0, 10000]?

How do you decode an integer pixel format into [0, 128] so it can be
fed through PQ EOTF?

And how do blocks after the PQ EOTF deal with the [0, 10000] domain,
when any other EOTF would produce [0, 1]?


Thanks,
pq

> 
> Signed-off-by: Joshua Ashton <jos...@froggi.es>
> Co-developed-by: Melissa Wen <m...@igalia.com>
> Signed-off-by: Melissa Wen <m...@igalia.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h           |  4 ++++
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h  | 14 ++++++++++++++
>  .../drm/amd/display/amdgpu_dm/amdgpu_dm_color.c    |  6 ++++++
>  .../drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c    | 13 +++++++++++++
>  4 files changed, 37 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
> index 6ef958a14e16..66bae0eed80c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
> @@ -359,6 +359,10 @@ struct amdgpu_mode_info {
>        * to go from scanout/encoded values to linear values.
>        */
>       struct drm_property *plane_degamma_tf_property;
> +     /**
> +      * @plane_hdr_mult_property:
> +      */
> +     struct drm_property *plane_hdr_mult_property;
>  };
>  
>  #define AMDGPU_MAX_BL_LEVEL 0xFF
> 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 f6251ed89684..44f17ac11a5f 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
> @@ -54,6 +54,9 @@
>  #define HDMI_AMD_VENDOR_SPECIFIC_DATA_BLOCK_IEEE_REGISTRATION_ID 0x00001A
>  #define AMD_VSDB_VERSION_3_FEATURECAP_REPLAYMODE 0x40
>  #define HDMI_AMD_VENDOR_SPECIFIC_DATA_BLOCK_VERSION_3 0x3
> +
> +#define AMDGPU_HDR_MULT_DEFAULT (0x100000000LL)
> +
>  /*
>  #include "include/amdgpu_dal_power_if.h"
>  #include "amdgpu_dm_irq.h"
> @@ -755,6 +758,17 @@ struct dm_plane_state {
>        * linearize.
>        */
>       enum amdgpu_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;
>  };
>  
>  struct dm_crtc_state {
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c 
> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c
> index 7f13bcdaf016..b891aaf5f7c1 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c
> @@ -203,6 +203,12 @@ amdgpu_dm_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, U64_MAX);
> +     if (!prop)
> +             return -ENOMEM;
> +     adev->mode_info.plane_hdr_mult_property = prop;
> +
>       return 0;
>  }
>  #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 0a955abb1abf..ab7f0332c431 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
> @@ -1331,6 +1331,7 @@ static void dm_drm_plane_reset(struct drm_plane *plane)
>  
>       __drm_atomic_helper_plane_reset(plane, &amdgpu_state->base);
>       amdgpu_state->degamma_tf = AMDGPU_TRANSFER_FUNCTION_DEFAULT;
> +     amdgpu_state->hdr_mult = AMDGPU_HDR_MULT_DEFAULT;
>  }
>  
>  static struct drm_plane_state *
> @@ -1354,6 +1355,7 @@ dm_drm_plane_duplicate_state(struct drm_plane *plane)
>               drm_property_blob_get(dm_plane_state->degamma_lut);
>  
>       dm_plane_state->degamma_tf = old_dm_plane_state->degamma_tf;
> +     dm_plane_state->hdr_mult = old_dm_plane_state->hdr_mult;
>  
>       return &dm_plane_state->base;
>  }
> @@ -1450,6 +1452,10 @@ dm_atomic_plane_attach_color_mgmt_properties(struct 
> amdgpu_display_manager *dm,
>                                          
> dm->adev->mode_info.plane_degamma_tf_property,
>                                          AMDGPU_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
> @@ -1476,6 +1482,11 @@ 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",
> @@ -1501,6 +1512,8 @@ 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;
>       }

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