On Mon, Sep 04, 2023 at 05:53:11AM +0300, Ville Syrjälä wrote: > On Thu, Aug 24, 2023 at 11:05:04AM +0300, Imre Deak wrote: > > For fractional bpp values passed to the function in a .4 fixed point > > format, the fractional part is currently ignored due to scaling bpp too > > early. Fix this by scaling the overhead factor instead and to avoid an > > overflow multiplying bpp with the overhead factor instead of the clock > > rate. > > > > While at it simplify the formula, and pass the expected fixed point bpp > > values in the kunit tests. > > > > Cc: Lyude Paul <lyude@xxxxxxxxxx> > > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx > > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> > > --- > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 7 ++----- > > drivers/gpu/drm/tests/drm_dp_mst_helper_test.c | 8 ++++---- > > 2 files changed, 6 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c > > index ed96cfcfa3040..bd0f35a0ea5fb 100644 > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c > > @@ -4712,12 +4712,9 @@ int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc) > > * factor in the numerator rather than the denominator to avoid > > * integer overflow > > */ > > + u32 bpp_m = (dsc ? 64 / 16 : 64) * 1006 * bpp; > > > > - if (dsc) > > - return DIV_ROUND_UP_ULL(mul_u32_u32(clock * (bpp / 16), 64 * 1006), > > - 8 * 54 * 1000 * 1000); > > - > > - return DIV_ROUND_UP_ULL(mul_u32_u32(clock * bpp, 64 * 1006), > > + return DIV_ROUND_UP_ULL(mul_u32_u32(clock, bpp_m), > > 8 * 54 * 1000 * 1000); > > I thought I sorted out this mess already... > https://patchwork.freedesktop.org/patch/535005/?series=117201&rev=3 > Apparently I forgot to push that. Looks ok, can use that instead. I thought clock * bpp could overflow, but probably not in practice. The test cases below would still need to be fixed. > > > } > > EXPORT_SYMBOL(drm_dp_calc_pbn_mode); > > diff --git a/drivers/gpu/drm/tests/drm_dp_mst_helper_test.c b/drivers/gpu/drm/tests/drm_dp_mst_helper_test.c > > index 545beea33e8c7..ea2182815ebe8 100644 > > --- a/drivers/gpu/drm/tests/drm_dp_mst_helper_test.c > > +++ b/drivers/gpu/drm/tests/drm_dp_mst_helper_test.c > > @@ -40,15 +40,15 @@ static const struct drm_dp_mst_calc_pbn_mode_test drm_dp_mst_calc_pbn_mode_cases > > }, > > { > > .clock = 332880, > > - .bpp = 24, > > + .bpp = 24 << 4, > > .dsc = true, > > - .expected = 50 > > + .expected = 1191 > > }, > > { > > .clock = 324540, > > - .bpp = 24, > > + .bpp = 24 << 4, > > .dsc = true, > > - .expected = 49 > > + .expected = 1161 > > }, > > }; > > > > -- > > 2.37.2 > > -- > Ville Syrjälä > Intel
