On Sat, 29 Feb 2020, Mario Kleiner <mario.kleiner.de@xxxxxxxxx> wrote: > This fixes a problem found on the MacBookPro 2017 Retina panel. > > The panel reports 10 bpc color depth in its EDID, and the > firmware chooses link settings at boot which support enough > bandwidth for 10 bpc (324000 kbit/sec = multiplier 0xc), > but the DP_MAX_LINK_RATE dpcd register only reports > 2.7 Gbps (multiplier value 0xa) as possible, in direct > contradiction of what the firmware successfully set up. > > This restricts the panel to 8 bpc, not providing the full > color depth of the panel. > > This patch adds a quirk specific to the MBP 2017 15" Retina > panel to add the additiional 324000 kbps link rate during > edp setup. > > Link to previous discussion of a different attempted fix > with Ville and Jani: > > https://patchwork.kernel.org/patch/11325935/ > > Signed-off-by: Mario Kleiner <mario.kleiner.de@xxxxxxxxx> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > Cc: Jani Nikula <jani.nikula@xxxxxxxxx> > --- > drivers/gpu/drm/drm_dp_helper.c | 2 ++ > drivers/gpu/drm/i915/display/intel_dp.c | 7 +++++++ > include/drm/drm_dp_helper.h | 7 +++++++ > 3 files changed, 16 insertions(+) > > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c > index 5a103e9b3c86..36a371c016cb 100644 > --- a/drivers/gpu/drm/drm_dp_helper.c > +++ b/drivers/gpu/drm/drm_dp_helper.c > @@ -1179,6 +1179,8 @@ static const struct dpcd_quirk dpcd_quirk_list[] = { > { OUI(0x00, 0x00, 0x00), DEVICE_ID('C', 'H', '7', '5', '1', '1'), false, BIT(DP_DPCD_QUIRK_NO_SINK_COUNT) }, > /* Synaptics DP1.4 MST hubs can support DSC without virtual DPCD */ > { OUI(0x90, 0xCC, 0x24), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) }, > + /* Apple MacBookPro 2017 15 inch eDP Retina panel reports too low DP_MAX_LINK_RATE */ > + { OUI(0x00, 0x10, 0xfa), DEVICE_ID(101, 68, 21, 101, 98, 97), false, BIT(DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS) }, > }; > > #undef OUI > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c > index 4074d83b1a5f..1f6bd659ad41 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp.c > +++ b/drivers/gpu/drm/i915/display/intel_dp.c > @@ -178,6 +178,13 @@ static void intel_dp_set_sink_rates(struct intel_dp *intel_dp) > } > > intel_dp->num_sink_rates = i; > + > + if (drm_dp_has_quirk(&intel_dp->desc, > + DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS)) { > + /* Needed for Apple MBP 2017, 15 inch eDP Retina panel */ > + intel_dp->sink_rates[i] = 324000; > + intel_dp->num_sink_rates++; > + } If we can isolate the quirk to this one function, I'll be happy. \o/ However, even if this might work on said machine, I'd prefer it if we didn't give the idea that you could just append a value in sink_rates (it must be sorted). How about putting something like this in the beginning of the function, to be a bit more explicit: if (quirk) { static const int quirk_rates[] = { 162000, 270000, 324000 }; memcpy(intel_dp->sink_rates, quirk_rates, sizeof(quirk_rates)); intel_dp->num_sink_rates = ARRAY_SIZE(quirk_rates); return; } BR, Jani. > } > > /* Get length of rates array potentially limited by max_rate. */ > diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h > index 262faf9e5e94..4b86a1f2a559 100644 > --- a/include/drm/drm_dp_helper.h > +++ b/include/drm/drm_dp_helper.h > @@ -1532,6 +1532,13 @@ enum drm_dp_quirk { > * The DSC caps can be read from the physical aux instead. > */ > DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD, > + /** > + * @DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS: > + * > + * The device supports a link rate of 3.24 Gbps (multiplier 0xc) despite > + * the DP_MAX_LINK_RATE register reporting a lower max multiplier. > + */ > + DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS, > }; > > /** -- Jani Nikula, Intel Open Source Graphics Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
