On 16.03.2023 14:17, Imre Deak wrote:
On TC ports the 4ms AUX timeout combined with the 5 * 32 retry
attempts during DPCD accesses adds a 640ms delay to each access if the
sink is disconnected. This in turn slows down a modeset during which the
sink is disconnected (for instance a disabling modeset).
Prevent the above delay by aborting AUX transfers on a TC port with a
disconnected sink.
The DP 1.4a link CTS (4.2.1.5 Source Device Inactive HPD / Inactive AUX
Test") also requires not to initiate AUX transfers on disconnected DP
ports in general, however this patch doesn't change the behavior on
non-TC ports, leaving that for a follow-up.
Reported-and-tested-by: Chris Chiu <chris.chiu@xxxxxxxxxxxxx>
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8279
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_dp_aux.c | 15 +++++++++++++--
drivers/gpu/drm/i915/display/intel_tc.c | 15 +++++++++++----
drivers/gpu/drm/i915/display/intel_tc.h | 1 +
3 files changed, 25 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c
index 96967e21c94c2..eb07dc5d87099 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
@@ -205,8 +205,19 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
for (i = 0; i < ARRAY_SIZE(ch_data); i++)
ch_data[i] = intel_dp->aux_ch_data_reg(intel_dp, i);
- if (is_tc_port)
+ if (is_tc_port) {
intel_tc_port_lock(dig_port);
+ /*
+ * Abort transfers on a disconnected port as required by
+ * DP 1.4a link CTS 4.2.1.5, also avoiding the long AUX
+ * timeouts that would otherwise happen.
+ * TODO: abort the transfer on non-TC ports as well.
Yes, for all ports this is definitely desirable, for example grep shows
about 15000 timeouts per one CI dmesg[1].
At least I hope, this cures the plague.
Reviewed-by: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
[1]:
http://gfx-ci.igk.intel.com/tree/drm-tip/CI_DRM_12884/fi-elk-e7500/dmesg0.txt
Regards
Andrzej
+ */
+ if (!intel_tc_port_connected_locked(&dig_port->base)) {
+ ret = -ENXIO;
+ goto out_unlock;
+ }
+ }
aux_domain = intel_aux_power_domain(dig_port);
@@ -367,7 +378,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
intel_pps_unlock(intel_dp, pps_wakeref);
intel_display_power_put_async(i915, aux_domain, aux_wakeref);
-
+out_unlock:
if (is_tc_port)
intel_tc_port_unlock(dig_port);
diff --git a/drivers/gpu/drm/i915/display/intel_tc.c b/drivers/gpu/drm/i915/display/intel_tc.c
index f45328712bff1..050f998284592 100644
--- a/drivers/gpu/drm/i915/display/intel_tc.c
+++ b/drivers/gpu/drm/i915/display/intel_tc.c
@@ -768,16 +768,23 @@ void intel_tc_port_sanitize_mode(struct intel_digital_port *dig_port)
* connected ports are usable, and avoids exposing to the users objects they
* can't really use.
*/
+bool intel_tc_port_connected_locked(struct intel_encoder *encoder)
+{
+ struct intel_digital_port *dig_port = enc_to_dig_port(encoder);
+ struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
+
+ drm_WARN_ON(&i915->drm, !intel_tc_port_ref_held(dig_port));
+
+ return tc_port_live_status_mask(dig_port) & BIT(dig_port->tc_mode);
+}
+
bool intel_tc_port_connected(struct intel_encoder *encoder)
{
struct intel_digital_port *dig_port = enc_to_dig_port(encoder);
bool is_connected;
intel_tc_port_lock(dig_port);
-
- is_connected = tc_port_live_status_mask(dig_port) &
- BIT(dig_port->tc_mode);
-
+ is_connected = intel_tc_port_connected_locked(encoder);
intel_tc_port_unlock(dig_port);
return is_connected;
diff --git a/drivers/gpu/drm/i915/display/intel_tc.h b/drivers/gpu/drm/i915/display/intel_tc.h
index d54082e2d5e8d..93813056043a5 100644
--- a/drivers/gpu/drm/i915/display/intel_tc.h
+++ b/drivers/gpu/drm/i915/display/intel_tc.h
@@ -17,6 +17,7 @@ bool intel_tc_port_in_dp_alt_mode(struct intel_digital_port *dig_port);
bool intel_tc_port_in_legacy_mode(struct intel_digital_port *dig_port);
bool intel_tc_port_connected(struct intel_encoder *encoder);
+bool intel_tc_port_connected_locked(struct intel_encoder *encoder);
u32 intel_tc_port_get_lane_mask(struct intel_digital_port *dig_port);
u32 intel_tc_port_get_pin_assignment_mask(struct intel_digital_port *dig_port);
