On Fri, May 12, 2023 at 11:54:09AM +0530, Ankit Nautiyal wrote: > As per Bsepc:49259, Bigjoiner BW check puts restriction on the > compressed bpp for a given CDCLK, pixelclock in cases where > Bigjoiner + DSC are used. > > Currently compressed bpp is computed first, and it is ensured that > the bpp will work at least with the max CDCLK freq. > > Since the CDCLK is computed later, lets account for Bigjoiner BW > check while calculating Min CDCLK. > > Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx> > --- > drivers/gpu/drm/i915/display/intel_cdclk.c | 49 ++++++++++++++++++---- > 1 file changed, 42 insertions(+), 7 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c > index 6bed75f1541a..3532640c5027 100644 > --- a/drivers/gpu/drm/i915/display/intel_cdclk.c > +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c > @@ -2520,6 +2520,46 @@ static int intel_planes_min_cdclk(const struct intel_crtc_state *crtc_state) > return min_cdclk; > } > > +static int intel_vdsc_min_cdclk(const struct intel_crtc_state *crtc_state) > +{ > + struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc); > + struct drm_i915_private *i915 = to_i915(crtc->base.dev); > + int min_cdclk = 0; > + > + /* > + * When we decide to use only one VDSC engine, since > + * each VDSC operates with 1 ppc throughput, pixel clock > + * cannot be higher than the VDSC clock (cdclk) > + */ > + if (!crtc_state->dsc.dsc_split) > + min_cdclk = max(min_cdclk, (int)crtc_state->pixel_rate); > + > + if (crtc_state->bigjoiner_pipes) { > + /* > + * According to Bigjoiner bw check: > + * compressed_bpp <= PPC * CDCLK * Big joiner Interface bits / Pixel clock > + * > + * We have already computed compressed_bpp, so now compute the min CDCLK that > + * is required to support this compressed_bpp. > + * > + * => CDCLK >= compressed_bpp * Pixel clock / (PPC * Bigjoiner Interface bits) > + * > + * Since Num of pipes joined = 2, and PPC = 2 with bigjoiner > + * => CDCLK >= compressed_bpp * pixel_rate / Bigjoiner Interface bits > + * > + * #TODO Bspec mentions to account for FEC overhead while using pixel clock. > + * Check if we need to use FEC overhead in the above calculations. > + */ > + int bigjoiner_interface_bits = DISPLAY_VER(i915) > 13 ? 36 : 24; > + int min_cdclk_bj = crtc_state->dsc.compressed_bpp * crtc_state->pixel_rate / > + bigjoiner_interface_bits; pixel_rate is the downscale adjusted thing, so it doesn't seem like the correct thing to use here. Hmm. Assuming that the single VDSC engine really throttles the entire pipe to 1 PPC then we should probably account for the 1 vs. 2 PPC difference in *_plane_min_cdclk() and intel_pixel_rate_to_cdclk() directly. Currently all of those assume 2 PPC. > + > + min_cdclk = max(min_cdclk, min_cdclk_bj); > + } > + > + return min_cdclk; > +} > + > int intel_crtc_compute_min_cdclk(const struct intel_crtc_state *crtc_state) > { > struct drm_i915_private *dev_priv = > @@ -2591,13 +2631,8 @@ int intel_crtc_compute_min_cdclk(const struct intel_crtc_state *crtc_state) > /* Account for additional needs from the planes */ > min_cdclk = max(intel_planes_min_cdclk(crtc_state), min_cdclk); > > - /* > - * When we decide to use only one VDSC engine, since > - * each VDSC operates with 1 ppc throughput, pixel clock > - * cannot be higher than the VDSC clock (cdclk) > - */ > - if (crtc_state->dsc.compression_enable && !crtc_state->dsc.dsc_split) > - min_cdclk = max(min_cdclk, (int)crtc_state->pixel_rate); > + if (crtc_state->dsc.compression_enable) > + min_cdclk = max(min_cdclk, intel_vdsc_min_cdclk(crtc_state)); > > /* > * HACK. Currently for TGL/DG2 platforms we calculate > -- > 2.25.1 -- Ville Syrjälä Intel