Hi Stan,
On Fri, 2023-03-10 at 16:40 +0200, Stanislav Lisovskiy wrote: > Currently in our bandwidth calculations for QGV > points we round up the calculations. > Recently there was an update to BSpec, recommending > to floor those calculations. > The reasoning behind this was that, overestimating > BW demand with that rounding can cause SAGV to use > next QGV point, even though the less demanding could > be used, thus resulting in waste of power. > > BSpec: 64636 > > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovs...@intel.com> > --- > drivers/gpu/drm/i915/display/intel_bw.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_bw.c > b/drivers/gpu/drm/i915/display/intel_bw.c > index 202321ffbe2a..8723ddd4d568 100644 > --- a/drivers/gpu/drm/i915/display/intel_bw.c > +++ b/drivers/gpu/drm/i915/display/intel_bw.c > @@ -50,7 +50,7 @@ static int dg1_mchbar_read_qgv_point_info(struct > drm_i915_private *dev_priv, > dclk_reference = 6; /* 6 * 16.666 MHz = 100 MHz */ > else > dclk_reference = 8; /* 8 * 16.666 MHz = 133 MHz */ > - sp->dclk = DIV_ROUND_UP((16667 * dclk_ratio * dclk_reference) + 500, > 1000); > + sp->dclk = ((16667 * dclk_ratio * dclk_reference) + 500) / 1000; > > val = intel_uncore_read(&dev_priv->uncore, > SKL_MC_BIOS_DATA_0_0_0_MCHBAR_PCU); > if (val & DG1_GEAR_TYPE) > @@ -87,7 +87,7 @@ static int icl_pcode_read_qgv_point_info(struct > drm_i915_private *dev_priv, > return ret; > > dclk = val & 0xffff; > - sp->dclk = DIV_ROUND_UP((16667 * dclk) + (DISPLAY_VER(dev_priv) > 11 > ? 500 : 0), 1000); > + sp->dclk = ((16667 * dclk) + (DISPLAY_VER(dev_priv) > 11 ? 500 : 0)) > / 1000; > sp->t_rp = (val & 0xff0000) >> 16; > sp->t_rcd = (val & 0xff000000) >> 24; > > @@ -179,7 +179,7 @@ static int mtl_read_qgv_point_info(struct > drm_i915_private *dev_priv, > val2 = intel_uncore_read(&dev_priv->uncore, > MTL_MEM_SS_INFO_QGV_POINT_HIGH(point)); > dclk = REG_FIELD_GET(MTL_DCLK_MASK, val); > - sp->dclk = DIV_ROUND_UP((16667 * dclk), 1000); > + sp->dclk = (16667 * dclk) / 1000; Not related to this patch. But as per Bspec 64631 and 64636 sp->dclk = (16667 * dclk + 500) / 1000; Does that need to be corrected as well? BR vinod > sp->t_rp = REG_FIELD_GET(MTL_TRP_MASK, val); > sp->t_rcd = REG_FIELD_GET(MTL_TRCD_MASK, val); > > @@ -425,7 +425,7 @@ static int icl_get_bw_info(struct drm_i915_private > *dev_priv, const struct > intel > */ > ct = max_t(int, sp->t_rc, sp->t_rp + sp->t_rcd + > (clpchgroup - 1) * qi.t_bl + sp->t_rdpre); > - bw = DIV_ROUND_UP(sp->dclk * clpchgroup * 32 * > num_channels, ct); > + bw = (sp->dclk * clpchgroup * 32 * num_channels) / ct; > > bi->deratedbw[j] = min(maxdebw, > bw * (100 - sa->derating) / > 100); > @@ -527,7 +527,7 @@ static int tgl_get_bw_info(struct drm_i915_private > *dev_priv, const struct > intel > */ > ct = max_t(int, sp->t_rc, sp->t_rp + sp->t_rcd + > (clpchgroup - 1) * qi.t_bl + sp->t_rdpre); > - bw = DIV_ROUND_UP(sp->dclk * clpchgroup * 32 * > num_channels, ct); > + bw = (sp->dclk * clpchgroup * 32 * num_channels) / ct; > > bi->deratedbw[j] = min(maxdebw, > bw * (100 - sa->derating) / > 100);
