diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_dp.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index fdd2cbc56fa3..de4219721cbc 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -3991,6 +3991,42 @@ intel_dp_link_down(struct intel_encoder *encoder, } } +static void +intel_dp_extended_receiver_capabilities(struct intel_dp *intel_dp) +{ + u8 dpcd_ext[6]; + + /* + * Prior to DP1.3 the bit represented by + * DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT was reserved. + * if it is set DP_DPCD_REV at 0000h could be at a value less than + * the true capability of the panel. The only way to check is to + * then compare 0000h and 2200h. + */ + if (!(intel_dp->dpcd[DP_TRAINING_AUX_RD_INTERVAL] & + DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT)) + return; + + if (drm_dp_dpcd_read(&intel_dp->aux, DP_DP13_DPCD_REV, + &dpcd_ext, sizeof(dpcd_ext)) != sizeof(dpcd_ext)) { + DRM_ERROR("DPCD failed read at extended capabilities\n"); + return; + } + + if (intel_dp->dpcd[DP_DPCD_REV] > dpcd_ext[DP_DPCD_REV]) { + DRM_DEBUG_KMS("DPCD extended DPCD rev less than base DPCD rev\n"); + return; + } + + if (!memcmp(intel_dp->dpcd, dpcd_ext, sizeof(dpcd_ext))) + return; + + DRM_DEBUG_KMS("Base DPCD: %*ph\n", + (int)sizeof(intel_dp->dpcd), intel_dp->dpcd); + + memcpy(intel_dp->dpcd, dpcd_ext, sizeof(dpcd_ext)); +} + bool intel_dp_read_dpcd(struct intel_dp *intel_dp) { @@ -3998,6 +4034,8 @@ intel_dp_read_dpcd(struct intel_dp *intel_dp) sizeof(intel_dp->dpcd)) < 0) return false; /* aux transfer failed */ + intel_dp_extended_receiver_capabilities(intel_dp); + DRM_DEBUG_KMS("DPCD: %*ph\n", (int) sizeof(intel_dp->dpcd), intel_dp->dpcd); return intel_dp->dpcd[DP_DPCD_REV] != 0; |