Thank you for the comments. I have made the corresponding changes to the revised patch in version No.3.
-----Original Message-----
From: Kandpal, Suraj <suraj.kandpal@xxxxxxxxx>
Sent: Wednesday, August 2, 2023 7:15 PM
To: Tseng, William <william.tseng@xxxxxxxxx>; intel-gfx@xxxxxxxxxxxxxxxxxxxxx
Cc: Heikkila, Juha-pekka <juha-pekka.heikkila@xxxxxxxxx>; Tseng, William <william.tseng@xxxxxxxxx>; Nautiyal, Ankit K <ankit.k.nautiyal@xxxxxxxxx>
Subject: RE: [PATCH] drm/i915/xelpd: Calculate first_line_bpg_offset for DSC 1.1
1.1
>
> This change is required for DSC 1.1 because the current calculation is
> for DSC
> 1.2 and may get a calculated value which is not recommended by DSC
> 1.1, for example, the calculated value at 8bpp becomes 15, not the
> value of 12 recommened by DSC 1.1.
>
> Cc: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
> Cc: Juha-Pekka Heikkil <juha-pekka.heikkila@xxxxxxxxx>
> Signed-off-by: William Tseng <william.tseng@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_vdsc.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c
> b/drivers/gpu/drm/i915/display/intel_vdsc.c
> index bd9116d2cd76..9b350f5f8ebb 100644
> --- a/drivers/gpu/drm/i915/display/intel_vdsc.c
> +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
> @@ -72,11 +72,18 @@ calculate_rc_params(struct drm_dsc_config
> *vdsc_cfg)
> int qp_bpc_modifier = (bpc - 8) * 2;
> u32 res, buf_i, bpp_i;
>
> - if (vdsc_cfg->slice_height >= 8)
> - vdsc_cfg->first_line_bpg_offset =
> - 12 + DIV_ROUND_UP((9 * min(34, vdsc_cfg-
> >slice_height - 8)), 100);
> - else
> - vdsc_cfg->first_line_bpg_offset = 2 * (vdsc_cfg-
> >slice_height - 1);
> + if (vdsc_cfg->dsc_version_minor == 2) {
I think the check here should be for minor version 1 and move the code in this block to the else block and vice versa as this 8 bpp corner case is applicable only to DSC 1.1
> + if (vdsc_cfg->slice_height >= 8)
> + vdsc_cfg->first_line_bpg_offset =
> + 12 + DIV_ROUND_UP((9 * min(34, vdsc_cfg-
> >slice_height - 8)), 100);
> + else
> + vdsc_cfg->first_line_bpg_offset = 2 * (vdsc_cfg-
> >slice_height - 1);
> + } else {
> + if (bpp == 8)
> + rc->first_line_bpg_offset = 12;
> + else
> + rc->first_line_bpg_offset = 15;
> + }
Add the section in DSC spec/ Cmodel from where one can verify this in comments
Regards,
Suraj Kandpal
>
> /* Our hw supports only 444 modes as of today */
> if (bpp >= 12)
> --
> 2.34.1
