[SRU][R][PATCH 06/22] drm/i915/dp: Handle a tunneling IRQ after acking it

[Werner Sembach]

From: Imre Deak <imre.deak at intel.com>

HPD IRQs in general should be handled after acking them. The

1. Read IRQ register (read DP_DEVICE_SERVICE_IRQ_VECTOR,
   DP_LINK_SERVICE_IRQ_VECTOR_ESI0)
2. Handle IRQ
3. Ack IRQ (write DP_DEVICE_SERVICE_IRQ_VECTOR,
   DP_LINK_SERVICE_IRQ_VECTOR_ESI0)

sequence would miss a new interrupt triggered after 2. and before 3.,
since the flag set in the IRQ register for this interrupt would be
cleared in step 3.

Fix the above by handling the IRQ after acking it.

Reviewed-by: Luca Coelho <luciano.coelho at intel.com>
Signed-off-by: Imre Deak <imre.deak at intel.com>
Link: https://patch.msgid.link/20260225164618.1261368-5-imre.deak@intel.com
Signed-off-by: Werner Sembach <wse at tuxedocomputers.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 5606c4c22d4af..6c977cff4fd46 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5370,17 +5370,10 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
 
 		drm_dbg_kms(display->drm, "DPRX ESI: %4ph\n", esi);
 
-		ack[3] |= esi[3] & LINK_STATUS_CHANGED;
+		ack[3] |= esi[3] & (LINK_STATUS_CHANGED | DP_TUNNELING_IRQ);
 
 		intel_dp_mst_hpd_irq(intel_dp, esi, ack);
 
-		if (esi[3] & DP_TUNNELING_IRQ) {
-			if (drm_dp_tunnel_handle_irq(display->dp_tunnel_mgr,
-						     &intel_dp->aux))
-				reprobe_needed = true;
-			ack[3] |= DP_TUNNELING_IRQ;
-		}
-
 		if (mem_is_zero(ack, sizeof(ack)))
 			break;
 
@@ -5392,6 +5385,10 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
 
 		if ((ack[3] & LINK_STATUS_CHANGED) || intel_dp->link.force_retrain)
 			intel_dp_check_link_state(intel_dp);
+
+		if ((ack[3] & DP_TUNNELING_IRQ) &&
+		    drm_dp_tunnel_handle_irq(display->dp_tunnel_mgr, &intel_dp->aux))
+			reprobe_needed = true;
 	}
 
 	return !reprobe_needed;
@@ -5694,18 +5691,18 @@ static bool intel_dp_check_link_service_irq(struct intel_dp *intel_dp)
 			      DP_LINK_SERVICE_IRQ_VECTOR_ESI0, &val) != 1 || !val)
 		return false;
 
-	if ((val & DP_TUNNELING_IRQ) &&
-	    drm_dp_tunnel_handle_irq(display->dp_tunnel_mgr,
-				     &intel_dp->aux))
-		reprobe_needed = true;
-
 	if (drm_dp_dpcd_writeb(&intel_dp->aux,
 			       DP_LINK_SERVICE_IRQ_VECTOR_ESI0, val) != 1)
-		return reprobe_needed;
+		return false;
 
 	if (val & HDMI_LINK_STATUS_CHANGED)
 		intel_dp_handle_hdmi_link_status_change(intel_dp);
 
+	if ((val & DP_TUNNELING_IRQ) &&
+	    drm_dp_tunnel_handle_irq(display->dp_tunnel_mgr,
+				     &intel_dp->aux))
+		reprobe_needed = true;
+
 	return reprobe_needed;
 }
 
-- 
2.43.0