Its observed that on AUX_CH failure, even if the retry is increased to
1000, it does not succeed. Either the command might be wrong or sink in
an unknown/sleep state can cause this. So try waking the sink device.
Before reading the DPCD caps wake the sink for eDP.
v2: Use poll_timeout_us (Jani N)
Add the reason, why this change is required (Ville)
v3: Wake sink only for eDP
Remove the dpcd probe set to true/false in wake_sink (Imre)
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/4391
Signed-off-by: Arun R Murthy <[email protected]>
---
drivers/gpu/drm/i915/display/intel_dp.c | 34 +++++++++++++++++++++++++
drivers/gpu/drm/i915/display/intel_dp.h | 1 +
2 files changed, 35 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
index 025e906b63a9..38ea4aad74de 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4705,6 +4705,38 @@ intel_edp_set_sink_rates(struct intel_dp *intel_dp)
intel_edp_set_data_override_rates(intel_dp);
}
+/* Spec says to try for 3 times, its doubled to add the software overhead */
+#define AUX_CH_WAKE_RETRY 6
+
+void intel_dp_wake_sink(struct intel_dp *intel_dp)
+{
+ u8 value = 0;
+ int ret = 0;
+
+ /*
+ * Wake the sink device
+ * Spec DP2.1 section 2.3.1.2 if AUX CH is powered down by writing 0x02
+ * to DP_SET_POWER dpcd reg, 1ms time would be required to wake it up
+ */
+ ret = poll_timeout_us(ret = drm_dp_dpcd_readb(&intel_dp->aux,
DP_SET_POWER, &value),
+ ret > 0,
+ 1000, AUX_CH_WAKE_RETRY * 1000, true);
+
+ /*
+ * If sink is in D3 then it may not respond to the AUX tx so
+ * wake it up to D3_AUX_ON state
+ * If the above poll_timeout_us fails, try waking the sink.
+ */
+ if (value == DP_SET_POWER_D3 || ret < 0) {
+ /* After setting to D0 need a min of 1ms to wake(Spec DP2.1 sec
2.3.1.2) */
+ drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER,
+ DP_SET_POWER_D0);
+ fsleep(1000);
+ drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER,
+ DP_SET_POWER_D3_AUX_ON);
+ }
+}
+
static bool
intel_edp_init_dpcd(struct intel_dp *intel_dp, struct intel_connector
*connector)
{
@@ -4713,6 +4745,8 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp, struct
intel_connector *connector
/* this function is meant to be called only once */
drm_WARN_ON(display->drm, intel_dp->dpcd[DP_DPCD_REV] != 0);
+ intel_dp_wake_sink(intel_dp);
+
if (drm_dp_read_dpcd_caps(&intel_dp->aux, intel_dp->dpcd) != 0)
return false;
diff --git a/drivers/gpu/drm/i915/display/intel_dp.h
b/drivers/gpu/drm/i915/display/intel_dp.h
index b0bbd5981f57..3f16077c0cc7 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -232,6 +232,7 @@ bool intel_dp_dotclk_valid(struct intel_display *display,
bool intel_dp_joiner_candidate_valid(struct intel_connector *connector,
int hdisplay,
int num_joined_pipes);
+void intel_dp_wake_sink(struct intel_dp *intel_dp);
#define for_each_joiner_candidate(__connector, __mode, __num_joined_pipes) \
for ((__num_joined_pipes) = 1; (__num_joined_pipes) <=
(I915_MAX_PIPES); (__num_joined_pipes)++) \
--
2.25.1
