From: Matt Atwood <matthew.s.atwood@xxxxxxxxx>
According to DP spec (2.9.3.1 of DP 1.4) if
EXTENDED_RECEIVER_CAPABILITY_FIELD_PRESENT is set the addresses in DPCD
02200h through 0220Fh shall contain the DPRX's true capability. These
values will match 00000h through 0000Fh, except for DPCD_REV,
MAX_LINK_RATE, DOWN_STREAM_PORT_PRESENT.
Read from DPCD once for all 3 values as this is an expensive operation.
Spec mentions that all of address space 02200h through 0220Fh should
contain the right information however currently only 3 values can
differ.
There is no address space in the intel_dp->dpcd struct for addresses
02200h through 0220Fh, and since so much of the data is a identical,
simply overwrite the values stored in 00000h through 0000Fh with the
values that can be overwritten from addresses 02200h through 0220Fh
Signed-off-by: Matt Atwood <matthew.s.atwood@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dp.c | 14 ++++++++++++++
include/drm/drm_dp_helper.h | 5 +++--
2 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index dde92e4af5d3..899ebc5cece6 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3738,6 +3738,20 @@ intel_dp_read_dpcd(struct intel_dp *intel_dp)
sizeof(intel_dp->dpcd)) < 0)
return false; /* aux transfer failed */
+ if (intel_dp->dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
+ DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT &&
+ intel_dp->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14) {
+ uint8_t dpcd_ext[16];
+
+ if (drm_dp_dpcd_read(&intel_dp->aux, DP_DP13_DPCD_REV,
+ &dpcd_ext, sizeof(dpcd_ext)) < 0)
+ return false; /* aux transfer failed */
+
+ intel_dp->dpcd[DP_DPCD_REV] = dpcd_ext[DP_DPCD_REV];
+ intel_dp->dpcd[DP_MAX_LINK_RATE] = dpcd_ext[DP_MAX_LINK_RATE];
+ intel_dp->dpcd[DP_DOWNSTREAMPORT_PRESENT] =
+ dpcd_ext[DP_DOWNSTREAMPORT_PRESENT];
+ }
DRM_DEBUG_KMS("DPCD: %*ph\n", (int) sizeof(intel_dp->dpcd), intel_dp->dpcd);
return intel_dp->dpcd[DP_DPCD_REV] != 0;
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index c01564991a9f..757bd5913f3d 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -123,8 +123,9 @@
# define DP_FRAMING_CHANGE_CAP (1 << 1)
# define DP_DPCD_DISPLAY_CONTROL_CAPABLE (1 << 3) /* edp v1.2 or higher */
-#define DP_TRAINING_AUX_RD_INTERVAL 0x00e /* XXX 1.2? */
-# define DP_TRAINING_AUX_RD_MASK 0x7F /* XXX 1.2? */
+#define DP_TRAINING_AUX_RD_INTERVAL 0x00e /* XXX 1.2? */
+# define DP_TRAINING_AUX_RD_MASK 0x7F /* XXX 1.2? */
+# define DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT (1 << 7)/* XXX 1.2? */
#define DP_ADAPTER_CAP 0x00f /* 1.2 */
# define DP_FORCE_LOAD_SENSE_CAP (1 << 0)
--
2.17.0
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