drm/i915/dp: Handle the DOWNSTREAM_PORT_STATUS_CHANGED event

Handle the DOWNSTREAM_PORT_STATUS_CHANGED event a branch device can use
to indicate the state change of a DFP connector on the branch device.
The event is signaled in the DP_LANE_ALIGN_STATUS_UPDATED DPCD register
setting a clear-on-read flag and triggering an HPD IRQ. Accordingly keep
a cached version of the flag, updating it whenever
DP_LANE_ALIGN_STATUS_UPDATED is read. Schedule a full connector
detection from the HPD IRQ handler if the cached flag is set and clear
the cached flag at the start of detection.

Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260225164618.1261368-7-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 8a2b37c7bccf453474904ef5b674d9399fe66f20..e189f8c39ccb440f99cd642de177b18f3b605753 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1796,6 +1796,7 @@ struct intel_dp {
        int link_rate;
        u8 lane_count;
        u8 sink_count;
+       bool downstream_port_changed;
        bool needs_modeset_retry;
        bool use_max_params;
        u8 dpcd[DP_RECEIVER_CAP_SIZE];

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 966e652e38d2dae39a349735ff0b3bf123892cc6..73703cd6e1cc879e3716948302966ebf8991cad5 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5556,7 +5556,14 @@ intel_dp_read_link_status(struct intel_dp *intel_dp, u8 link_status[DP_LINK_STAT
                err = drm_dp_dpcd_read_phy_link_status(&intel_dp->aux, DP_PHY_DPRX,
                                                       link_status);
 
-       return err;
+       if (err)
+               return err;
+
+       if (link_status[DP_LANE_ALIGN_STATUS_UPDATED - DP_LANE0_1_STATUS] &
+           DP_DOWNSTREAM_PORT_STATUS_CHANGED)
+               WRITE_ONCE(intel_dp->downstream_port_changed, true);
+
+       return 0;
 }
 
 static bool
@@ -5876,6 +5883,11 @@ intel_dp_short_pulse(struct intel_dp *intel_dp)
 
        intel_dp_check_link_state(intel_dp);
 
+       if (READ_ONCE(intel_dp->downstream_port_changed)) {
+               WRITE_ONCE(intel_dp->downstream_port_changed, false);
+               reprobe_needed = true;
+       }
+
        intel_psr_short_pulse(intel_dp);
 
        if (intel_alpm_get_error(intel_dp)) {
@@ -5901,6 +5913,8 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp)
        if (drm_WARN_ON(display->drm, intel_dp_is_edp(intel_dp)))
                return connector_status_connected;
 
+       WRITE_ONCE(intel_dp->downstream_port_changed, false);
+
        intel_lspcon_resume(dig_port);
 
        if (!intel_dp_get_dpcd(intel_dp))