On Thu, 02 Feb 2023, Suraj Kandpal <[email protected]> wrote: > According to Bpec: 49259 VDSC spec implies that 108 lines is an optimal > slice height, but any size can be used as long as vertical active > integer multiple and maximum vertical slice count requirements are met.
The commit message and subject should really indicate that this increases the slice height considerably. It's a 13.5x increase at a minimum, could be much more. Seems misleading to call it "fix logic", as if there's a small issue somewhere. Bspec references should be here: Bspec: 49259 > Cc: Ankit Nautiyal <[email protected]> > Cc: Swati Sharma <[email protected]> > Signed-off-by: Suraj Kandpal <[email protected]> > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c > b/drivers/gpu/drm/i915/display/intel_dp.c > index 62cbab7402e9..7bd2e56ef0fa 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp.c > +++ b/drivers/gpu/drm/i915/display/intel_dp.c > @@ -1415,6 +1415,22 @@ static int intel_dp_sink_dsc_version_minor(struct > intel_dp *intel_dp) > DP_DSC_MINOR_SHIFT; > } > > +static int intel_dp_get_slice_height(int vactive) intel_dp_dsc_get_slice_height > +{ > + int slice_height; > + > + /* > + * VDSC spec implies that 108 lines is an optimal slice height, Please be more specific with spec references than vague "VSDC spec". Spec version is required at a minimum. Section and section title are a nice bonus. > + * but any size can be used as long as vertical active integer > + * multiple and maximum vertical slice count requirements are met. > + */ > + for (slice_height = 108; slice_height <= vactive; slice_height += 2) Where does it say 108 is a minimum, and you should go up only...? > + if (!(vactive % slice_height)) Matter of taste, but please use (vactive % slice_height == 0) for clarity on computations like this. > + return slice_height; > + > + return 0; I guess it's unlikely we ever hit here, but you could have the old code as fallback and never return 0. Because you don't check for 0 in the caller anyway. Also makes me wonder why we have intel_hdmi_dsc_get_slice_height() separately, with almost identical implementation. Maybe we should consolidate. > +} > + > static int intel_dp_dsc_compute_params(struct intel_encoder *encoder, > struct intel_crtc_state *crtc_state) > { > @@ -1433,17 +1449,7 @@ static int intel_dp_dsc_compute_params(struct > intel_encoder *encoder, > vdsc_cfg->rc_model_size = DSC_RC_MODEL_SIZE_CONST; > vdsc_cfg->pic_height = crtc_state->hw.adjusted_mode.crtc_vdisplay; > > - /* > - * Slice Height of 8 works for all currently available panels. So start > - * with that if pic_height is an integral multiple of 8. Eventually add > - * logic to try multiple slice heights. > - */ > - if (vdsc_cfg->pic_height % 8 == 0) > - vdsc_cfg->slice_height = 8; > - else if (vdsc_cfg->pic_height % 4 == 0) > - vdsc_cfg->slice_height = 4; > - else > - vdsc_cfg->slice_height = 2; > + vdsc_cfg->slice_height = > intel_dp_get_slice_height(vdsc_cfg->pic_height); > > ret = intel_dsc_compute_params(crtc_state); > if (ret) -- Jani Nikula, Intel Open Source Graphics Center
