On Tue, 23 May 2023, Suraj Kandpal <suraj.kandpal@xxxxxxxxx> wrote:
> Move rc_param calculation for native_420 into calculate_rc_parameter.
Why?
Please always answer the question "why" in the commit message, even if
briefly.
>
> Cc: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
> Signed-off-by: Suraj Kandpal <suraj.kandpal@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_vdsc.c | 28 +++++++++++++----------
> 1 file changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
> index bd9116d2cd76..c64a38363e02 100644
> --- a/drivers/gpu/drm/i915/display/intel_vdsc.c
> +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
> @@ -78,6 +78,22 @@ calculate_rc_params(struct drm_dsc_config *vdsc_cfg)
> else
> vdsc_cfg->first_line_bpg_offset = 2 * (vdsc_cfg->slice_height - 1);
>
> + /* According to DSC 1.2 specs in Section 4.1 if native_420 is set:
> + * -second_line_bpg_offset is 12 in general and equal to 2*(slice_height-1) if slice
> + * height < 8.
> + * -second_line_offset_adj is 512 as shown by emperical values to yeild best chroma
> + * preservation in second line.
> + */
> + if (vdsc_cfg->native_420) {
> + if (vdsc_cfg->slice_height >= 8)
> + vdsc_cfg->second_line_bpg_offset = 12;
> + else
> + vdsc_cfg->second_line_bpg_offset =
> + 2 * (vdsc_cfg->slice_height - 1);
> +
> + vdsc_cfg->second_line_offset_adj = 512;
> + }
> +
> /* Our hw supports only 444 modes as of today */
> if (bpp >= 12)
> vdsc_cfg->initial_offset = 2048;
> @@ -192,24 +208,12 @@ int intel_dsc_compute_params(struct intel_crtc_state *pipe_config)
> /*
> * According to DSC 1.2 specs in Section 4.1 if native_420 is set:
> * -We need to double the current bpp.
> - * -second_line_bpg_offset is 12 in general and equal to 2*(slice_height-1) if slice
> - * height < 8.
> - * -second_line_offset_adj is 512 as shown by emperical values to yeild best chroma
> - * preservation in second line.
> * -nsl_bpg_offset is calculated as second_line_offset/slice_height -1 then rounded
> * up to 16 fractional bits, we left shift second line offset by 11 to preserve 11
> * fractional bits.
> */
> if (vdsc_cfg->native_420) {
> vdsc_cfg->bits_per_pixel <<= 1;
> -
> - if (vdsc_cfg->slice_height >= 8)
> - vdsc_cfg->second_line_bpg_offset = 12;
> - else
> - vdsc_cfg->second_line_bpg_offset =
> - 2 * (vdsc_cfg->slice_height - 1);
> -
> - vdsc_cfg->second_line_offset_adj = 512;
> vdsc_cfg->nsl_bpg_offset = DIV_ROUND_UP(vdsc_cfg->second_line_bpg_offset << 11,
> vdsc_cfg->slice_height - 1);
> }
--
Jani Nikula, Intel Open Source Graphics Center
