Re: [v3] drm/i915/icl: Handle YCbCr to RGB conversion for BT2020 case

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, May 09, 2019 at 09:57:19PM +0530, Uma Shankar wrote:
> Currently input csc for YCbCR to RGB conversion handles only
> BT601 and Bt709. Extending it to support BT2020 as well.
> 
> v2: Fixed the co-efficients for LR to FR conversion,
> as suggested by Ville.
> 
> v3: Fixed Y Pre-offset in case of Full Range YCbCr as suggested
> by Ville.
> 
> Signed-off-by: Uma Shankar <uma.shankar@intel.com>
> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_sprite.c | 31 +++++++++++++++++++++++++++++--
>  1 file changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
> index 2913e89..c9c970f 100644
> --- a/drivers/gpu/drm/i915/intel_sprite.c
> +++ b/drivers/gpu/drm/i915/intel_sprite.c
> @@ -433,6 +433,18 @@ int intel_plane_check_src_coordinates(struct intel_plane_state *plane_state)
>  			0x9EF8, 0x7800, 0xABF8,
>  			0x0, 0x7800,  0x7ED8,
>  		},
> +		/*
> +		 * BT.2020 full range YCbCr -> full range RGB
> +		 * The matrix required is :
> +		 * [1.000, 0.000, 1.474,
> +		 *  1.000, -0.1645, -0.5713,
> +		 *  1.000, 1.8814, 0.0000]
> +		 */
> +		[DRM_COLOR_YCBCR_BT2020] = {
> +			0x7BC8, 0x7800, 0x0,
> +			0x8928, 0x7800, 0xAA88,
> +			0x0, 0x7800, 0x7F10,
> +		},
>  	};
>  
>  	/* Matrix for Limited Range to Full Range Conversion */
> @@ -461,6 +473,18 @@ int intel_plane_check_src_coordinates(struct intel_plane_state *plane_state)
>  			0x8888, 0x7918, 0xADA8,
>  			0x0, 0x7918,  0x6870,
>  		},
> +		/*
> +		 * BT.2020 Limited range YCbCr -> full range RGB
> +		 * The matrix required is :
> +		 * [1.164, 0.000, 1.678,
> +		 *  1.164, -0.1873, -0.6504,
> +		 *  1.164, 2.1417, 0.0000]
> +		 */
> +		[DRM_COLOR_YCBCR_BT2020] = {
> +			0x7D70, 0x7950, 0x0,
> +			0x8A68, 0x7950, 0xAC00,
> +			0x0, 0x7950, 0x6890,
> +		},
>  	};
>  	const u16 *csc;
>  
> @@ -481,8 +505,11 @@ int intel_plane_check_src_coordinates(struct intel_plane_state *plane_state)
>  
>  	I915_WRITE_FW(PLANE_INPUT_CSC_PREOFF(pipe, plane_id, 0),
>  		      PREOFF_YUV_TO_RGB_HI);
> -	I915_WRITE_FW(PLANE_INPUT_CSC_PREOFF(pipe, plane_id, 1),
> -		      PREOFF_YUV_TO_RGB_ME);
> +	if (plane_state->base.color_range == DRM_COLOR_YCBCR_FULL_RANGE)
> +		I915_WRITE_FW(PLANE_INPUT_CSC_PREOFF(pipe, plane_id, 1), 0);
> +	else
> +		I915_WRITE_FW(PLANE_INPUT_CSC_PREOFF(pipe, plane_id, 1),
> +			      PREOFF_YUV_TO_RGB_ME);

I think this could probably be a separate patch since it affects
BT.601/BT.709 as well. Oh, and the matrix coefficients for 601/709 seem
similarly off as what you had in this patch originally. So I think we
want yet another patch to fix those up. Just a bit surprised that even
the current igts pass with those coefficients.

Anyways,
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
(you can keep this on both patch if you split).

PS. pls. cc me @linux.intel.com rather than @intel.com. I generally 
ignore patches going to the @intel.com address. Not that I really
care one way or the other whether a patch was cc:d to me anyway.

>  	I915_WRITE_FW(PLANE_INPUT_CSC_PREOFF(pipe, plane_id, 2),
>  		      PREOFF_YUV_TO_RGB_LO);
>  	I915_WRITE_FW(PLANE_INPUT_CSC_POSTOFF(pipe, plane_id, 0), 0x0);
> -- 
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel
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