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. + */ + 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); -- 2.37.1
