On Wed, Jun 12, 2024 at 04:35:36PM +0300, Luca Coelho wrote: > Hi Imre, > > On Tue, 2024-06-11 at 18:33 +0300, Imre Deak wrote: > > The branch or sink device decompressing a stream may have a limitation > > on the input/uncompressed BPP, which is lower than the base line BPP > > (determined by the sink's EDID). In some cases a stream with an input > > BPP higher than this limit will be converted automatically by the device > > decompressing the stream, by truncating the BPP, however in some cases > > - seen at least in Dell dock's DP->HDMI converters - the decompression > > will fail. > > > > Fix the above by limiting the input BPP correctly. This is done already > > correctly for SST outputs. > > > > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> > > --- > > drivers/gpu/drm/i915/display/intel_dp_mst.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c > > index 00fdcbc28e9b7..15c20bedea091 100644 > > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c > > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c > > @@ -349,6 +349,8 @@ static int intel_dp_dsc_mst_compute_link_config(struct intel_encoder *encoder, > > if (max_bpp > sink_max_bpp) > > max_bpp = sink_max_bpp; > > > > + crtc_state->pipe_bpp = max_bpp; > > + > > max_compressed_bpp = intel_dp_dsc_sink_max_compressed_bpp(connector, > > crtc_state, > > max_bpp / 3); > > Wouldn't it be better to make the assignment in > intel_dp_dsc_sink_max_compressed_bpp(), since that function is already > making modifications to crtc_state? Agreed, this is less than ideal atm. The whole MST DSC state computation would need a refactor, at least to sanitize it wrt. the MST/non-DSC and the SST DSC counterparts (also planned by others). Hence, it made sense to keep this fix simple. Also, the rational I saw for this way was that the input/uncompressed bpp (max_bpp above), which isn't relavant in the non-DSC case, is computed in intel_dp_dsc_mst_compute_link_config() and intel_dp_mst_find_vcpi_slots_for_bpp() would only compute the output/compressed bpp (relevant to both DSC and non-DSC case). Imo in the end the computation for these two cases should be separated into their own functions, instead of passing a 'bool dsc' param to a common function handling both cases. > There is another caller, but I think it may benefit from the same check. For the non-DSC case the above limit doesn't apply (at least I'm not aware of it). > But this is just a nitpick. Either way, you have: > > Reviewed-by: Luca Coelho <luciano.coelho@xxxxxxxxx> Thanks! > > -- > Cheers, > Luca.
