[PATCH 04/20] drm/i915/dp: Handle a tunneling IRQ after acking it

[Imre Deak]

From: Imre Deak <imre.deak at gmail.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.

Signed-off-by: Imre Deak <imre.deak at gmail.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 285cd9a5d4a7b..453416b9e9bec 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5099,17 +5099,10 @@ 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;
 
@@ -5121,6 +5114,10 @@ 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;
@@ -5423,18 +5420,18 @@ 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;
 }
 
-- 
2.44.2