From: Thierry Reding <treding@xxxxxxxxxx>
Store the AUX read interval from DPCD, so that it can be used to wait
for the durations given in the specification during link training.
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
drivers/gpu/drm/drm_dp_helper.c | 4 ++++
include/drm/drm_dp_helper.h | 17 +++++++++++++++++
2 files changed, 21 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 76ac68bc1042..da519acfeba7 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -339,6 +339,7 @@ static void drm_dp_link_reset(struct drm_dp_link *link)
link->max_lanes = 0;
drm_dp_link_caps_reset(&link->caps);
+ link->aux_rd_interval = 0;
link->edp = 0;
link->rate = 0;
@@ -392,6 +393,9 @@ int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link)
link->edp = edp_revs[value];
}
+ /* DP_TRAINING_AUX_RD_INTERVAL is in units of 4 milliseconds */
+ link->aux_rd_interval = drm_dp_aux_rd_interval(values);
+
link->rate = link->max_rate;
link->lanes = link->max_lanes;
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 825aaf4e8c71..20ae0e413b64 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -678,6 +678,22 @@ drm_dp_alternate_scrambler_reset_cap(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
DP_ALTERNATE_SCRAMBLER_RESET_CAP;
}
+/**
+ * drm_dp_read_aux_interval() - read the AUX read interval from the DPCD
+ * @dpcd: receiver capacity buffer
+ *
+ * Reads the AUX read interval (in microseconds) from the DPCD. Note that the
+ * TRAINING_AUX_RD_INTERVAL stores the value in units of 4 milliseconds.
+ *
+ * Returns:
+ * The read AUX interval in microseconds.
+ */
+static inline unsigned int
+drm_dp_aux_rd_interval(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+ return dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4000;
+}
+
/*
* DisplayPort AUX channel
*/
@@ -805,6 +821,7 @@ struct drm_dp_link {
unsigned int max_lanes;
struct drm_dp_link_caps caps;
+ unsigned int aux_rd_interval;
unsigned char edp;
unsigned int rate;
--
2.5.0
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