On Wed, 28 Jan 2026, Suraj Kandpal <[email protected]> wrote: > Add a meaningful return to intel_dp_read_dsc_dpcd so tha we avoid > unwanted DPCD reads which are not needed once we know DSC DPCD > read fails. While we are at it remove the drm_err since we do not > shout error during intel_dp_detect phase since it may take time > to come up after pps_on is called for eDP scenario.
Please pay more attention to the commit message. > Signed-off-by: Suraj Kandpal <[email protected]> > --- > drivers/gpu/drm/i915/display/intel_dp.c | 24 +++++++++++++++--------- > 1 file changed, 15 insertions(+), 9 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c > b/drivers/gpu/drm/i915/display/intel_dp.c > index 79fd3b8d8b25..d2ed8ec145a2 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp.c > +++ b/drivers/gpu/drm/i915/display/intel_dp.c > @@ -4281,20 +4281,21 @@ static bool intel_dp_get_colorimetry_status(struct > intel_dp *intel_dp) > return dprx & DP_VSC_SDP_EXT_FOR_COLORIMETRY_SUPPORTED; > } > > -static void intel_dp_read_dsc_dpcd(struct drm_dp_aux *aux, > - u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE]) > +static int intel_dp_read_dsc_dpcd(struct drm_dp_aux *aux, > + u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE]) > { > if (drm_dp_dpcd_read(aux, DP_DSC_SUPPORT, dsc_dpcd, > DP_DSC_RECEIVER_CAP_SIZE) < 0) { > - drm_err(aux->drm_dev, > - "Failed to read DPCD register 0x%x\n", > - DP_DSC_SUPPORT); > - return; > + drm_dbg_kms(aux->drm_dev, > + "Could not read DSC DPCD register 0x%x\n", > + DP_DSC_SUPPORT); > + return -EINVAL; If we want to do this properly, then let's propagate the actual error code instead of inventing -EINVAL here. And switch to drm_dp_dpcd_read_data(), which returns an error if not all bytes were transferred (also a case the current implementation completely ignores). Finlly, the debug logging could log the error code. A combo of %pe in the format string and ERR_PTR(ret) in the corresponding parameter will do it nicely. > } > > drm_dbg_kms(aux->drm_dev, "DSC DPCD: %*ph\n", > DP_DSC_RECEIVER_CAP_SIZE, > dsc_dpcd); > + return 0; > } > > static void init_dsc_overall_throughput_limits(struct intel_connector > *connector, bool is_branch) > @@ -4345,8 +4346,11 @@ void intel_dp_get_dsc_sink_cap(u8 dpcd_rev, > if (dpcd_rev < DP_DPCD_REV_14) > return; > > - intel_dp_read_dsc_dpcd(connector->dp.dsc_decompression_aux, > - connector->dp.dsc_dpcd); > + if (intel_dp_read_dsc_dpcd(connector->dp.dsc_decompression_aux, > + connector->dp.dsc_dpcd) < 0) { > + drm_err(display->drm, "Failed to read DSC DPCD register\n"); > + return; > + } > > if (drm_dp_dpcd_readb(connector->dp.dsc_decompression_aux, > DP_FEC_CAPABILITY, > &connector->dp.fec_capability) < 0) { > @@ -4376,7 +4380,9 @@ static void intel_edp_get_dsc_sink_cap(u8 edp_dpcd_rev, > struct intel_connector * > if (edp_dpcd_rev < DP_EDP_14) > return; > > - intel_dp_read_dsc_dpcd(connector->dp.dsc_decompression_aux, > connector->dp.dsc_dpcd); > + if (intel_dp_read_dsc_dpcd(connector->dp.dsc_decompression_aux, > + connector->dp.dsc_dpcd) < 0) > + return; > > if (connector->dp.dsc_dpcd[0] & DP_DSC_DECOMPRESSION_IS_SUPPORTED) > init_dsc_overall_throughput_limits(connector, false); -- Jani Nikula, Intel
