RE: [PATCH v2 1/8] drm/i915/hdmi: Split the intel_hdmi_dsc_get_bpp()

> Subject: [PATCH v2 1/8] drm/i915/hdmi: Split the intel_hdmi_dsc_get_bpp()
> 
> Split the intel_hdmi_dsc_get_bpp() into two helper functions that can be called
> independently.
> 
> While at it, improve the comments in the helper.
> 
> Signed-off-by: Ankit Nautiyal <[email protected]>

LGTM,
Reviewed-by: Suraj Kandpal <[email protected]>

> ---
>  drivers/gpu/drm/i915/display/intel_hdmi.c | 97 ++++++++++++++---------
>  1 file changed, 59 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c
> b/drivers/gpu/drm/i915/display/intel_hdmi.c
> index 9b637e38a1a5..df88d7c141f7 100644
> --- a/drivers/gpu/drm/i915/display/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
> @@ -3325,61 +3325,49 @@ intel_hdmi_dsc_get_num_slices(const struct
> drm_display_mode *mode,
>  	return target_slices;
>  }
> 
> -/*
> - * intel_hdmi_dsc_get_bpp - get the appropriate compressed bits_per_pixel
> based on
> - * source and sink capabilities.
> - *
> - * @src_fraction_bpp: fractional bpp supported by the source
> - * @slice_width: dsc slice width supported by the source and sink
> - * @num_slices: num of slices supported by the source and sink
> - * @output_format: video output format
> - * @bpc: bits per color
> - * @hdmi_all_bpp: sink supports decoding of 1/16th bpp setting
> - * @hdmi_max_chunk_bytes: max bytes in a line of chunks supported by sink
> - *
> - * @return: compressed bits_per_pixel in step of 1/16 of bits_per_pixel
> - */
> -int
> -intel_hdmi_dsc_get_bpp(int src_fractional_bpp, int slice_width, int num_slices,
> -		       enum intel_output_format output_format, int bpc,
> -		       bool hdmi_all_bpp, int hdmi_max_chunk_bytes)
> +static void
> +get_dsc_min_max_bpp(enum intel_output_format output_format, u8 bpc,
> +		    bool hdmi_all_bpp, int *min_dsc_bpp, int *max_dsc_bpp)
>  {
> -	int max_dsc_bpp, min_dsc_bpp;
> -	int target_bytes;
> -	bool bpp_found = false;
> -	int bpp_decrement_x16;
> -	int bpp_target;
> -	int bpp_target_x16;
> -
>  	/*
> -	 * Get min bpp and max bpp as per Table 7.23, in HDMI2.1 spec
> +	 * Get min bpp and max bpp that can be supported for a
> +	 * given bpc and output format.
>  	 * Start with the max bpp and keep on decrementing with
> -	 * fractional bpp, if supported by PCON DSC encoder
> +	 * fractional bpp, if supported by the DSC encoder
>  	 *
>  	 * for each bpp we check if no of bytes can be supported by HDMI sink
>  	 */
> 
>  	if (output_format == INTEL_OUTPUT_FORMAT_YCBCR420) {
> -		min_dsc_bpp = 6;
> -		max_dsc_bpp = 3 * bpc / 2;
> +		*min_dsc_bpp = 6;
> +		*max_dsc_bpp = 3 * bpc / 2;
>  	} else if (output_format == INTEL_OUTPUT_FORMAT_YCBCR444 ||
>  		   output_format == INTEL_OUTPUT_FORMAT_RGB) {
> -		min_dsc_bpp = 8;
> -		max_dsc_bpp = 3 * bpc;
> +		*min_dsc_bpp = 8;
> +		*max_dsc_bpp = 3 * bpc;
>  	} else {
>  		/* Assuming 4:2:2 encoding */
> -		min_dsc_bpp = 7;
> -		max_dsc_bpp = 2 * bpc;
> +		*min_dsc_bpp = 7;
> +		*max_dsc_bpp = 2 * bpc;
>  	}
> 
>  	/*
> -	 * Taking into account if all dsc_all_bpp supported by HDMI2.1 sink
> -	 * Section 7.7.34 : Source shall not enable compressed Video
> -	 * Transport with bpp_target settings above 12 bpp unless
> -	 * DSC_all_bpp is set to 1.
> +	 * Don't enable DSC bpp_target settings above 12 bpp,
> +	 * unless DSC_all_bpp is set to 1.
>  	 */
>  	if (!hdmi_all_bpp)
> -		max_dsc_bpp = min(max_dsc_bpp, 12);
> +		*max_dsc_bpp = min(*max_dsc_bpp, 12); }
> +
> +static int
> +get_dsc_compressed_bpp(int num_slices, int slice_width, int
> hdmi_max_chunk_bytes,
> +		       int src_fractional_bpp, int min_dsc_bpp, int max_dsc_bpp)
> {
> +	int target_bytes;
> +	bool bpp_found = false;
> +	int bpp_decrement_x16;
> +	int bpp_target;
> +	int bpp_target_x16;
> 
>  	/*
>  	 * The Sink has a limit of compressed data in bytes for a scanline, @@ -
> 3423,6 +3411,39 @@ intel_hdmi_dsc_get_bpp(int src_fractional_bpp, int
> slice_width, int num_slices,
>  	return 0;
>  }
> 
> +/*
> + * intel_hdmi_dsc_get_bpp - get the appropriate compressed
> +bits_per_pixel based on
> + * source and sink capabilities.
> + *
> + * @src_fraction_bpp: fractional bpp supported by the source
> + * @slice_width: dsc slice width supported by the source and sink
> + * @num_slices: num of slices supported by the source and sink
> + * @output_format: video output format
> + * @bpc: bits per color
> + * @hdmi_all_bpp: sink supports decoding of 1/16th bpp setting
> + * @hdmi_max_chunk_bytes: max bytes in a line of chunks supported by
> +sink
> + *
> + * @return: compressed bits_per_pixel in step of 1/16 of bits_per_pixel
> +*/ int intel_hdmi_dsc_get_bpp(int src_fractional_bpp, int slice_width,
> +int num_slices,
> +		       enum intel_output_format output_format, int bpc,
> +		       bool hdmi_all_bpp, int hdmi_max_chunk_bytes) {
> +	int max_dsc_bpp, min_dsc_bpp;
> +	int dsc_bpp_x16;
> +
> +	get_dsc_min_max_bpp(output_format, bpc, hdmi_all_bpp,
> +			    &min_dsc_bpp, &max_dsc_bpp);
> +
> +	dsc_bpp_x16 = get_dsc_compressed_bpp(num_slices, slice_width,
> +					     hdmi_max_chunk_bytes,
> +					     src_fractional_bpp,
> +					     min_dsc_bpp, max_dsc_bpp);
> +
> +	return dsc_bpp_x16;
> +}
> +
>  int intel_hdmi_sink_max_frl_rate(struct drm_connector *connector)  {
>  	int max_lanes = connector->display_info.hdmi.max_lanes;
> --
> 2.50.1