On Fri, 04 Aug 2023, Suraj Kandpal <suraj.kandpal@xxxxxxxxx> wrote: > On checking DSC1.1 Errata and DSC 1.2 spec the current formula > we were using was incorrect to calculate first_line_bpg_offset. > The new fixed formula is derived from C model. > > --v2 > -Use clamp function in linux/minmax.h [Ankit] > > --v3 > -remove linux/minmax.h header > > Signed-off-by: Suraj Kandpal <suraj.kandpal@xxxxxxxxx> > Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx> Should this be: Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9102 > --- > drivers/gpu/drm/i915/display/intel_vdsc.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c > index 9d76c2756784..e4c395b4dc46 100644 > --- a/drivers/gpu/drm/i915/display/intel_vdsc.c > +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c > @@ -80,13 +80,19 @@ calculate_rc_params(struct drm_dsc_config *vdsc_cfg) > int bpc = vdsc_cfg->bits_per_component; > int bpp = vdsc_cfg->bits_per_pixel >> 4; > int qp_bpc_modifier = (bpc - 8) * 2; > + int uncompressed_bpg_rate; > + int first_line_bpg_offset; > 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); > + first_line_bpg_offset = > + 12 + (9 * min(34, vdsc_cfg->slice_height - 8)) / 100; > else > - vdsc_cfg->first_line_bpg_offset = 2 * (vdsc_cfg->slice_height - 1); > + first_line_bpg_offset = 2 * (vdsc_cfg->slice_height - 1); > + > + uncompressed_bpg_rate = (3 * bpc + (vdsc_cfg->convert_rgb ? 0 : 2)) * 3; > + vdsc_cfg->first_line_bpg_offset = clamp(first_line_bpg_offset, 0, > + uncompressed_bpg_rate - 3 * bpp); > > /* > * According to DSC 1.2 spec in Section 4.1 if native_420 is set: -- Jani Nikula, Intel Open Source Graphics Center
