An AUX access failure during HPD IRQ handling should be handled by
falling back to a full connector detection, ensure that if the failure
happens while reading/acking a link service IRQ.

While at it add code comment documenting the return value of
intel_dp_check_link_service_irq().

v2: Docuement intel_dp_check_link_service_irq()'s return value. (Jani)

Cc: Jani Nikula <[email protected]>
Reviewed-by: Luca Coelho <[email protected]>
Signed-off-by: Imre Deak <[email protected]>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c 
b/drivers/gpu/drm/i915/display/intel_dp.c
index 4a44059362139..f7e91fc16b5dd 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5803,6 +5803,11 @@ static bool intel_dp_check_device_service_irq(struct 
intel_dp *intel_dp)
        return false;
 }
 
+/*
+ * Return %true if a full connector reprobe is required due to a failure while
+ * reading or acking the link service IRQs or if the reprobing is required
+ * after handling a link service IRQ event.
+ */
 static bool intel_dp_check_link_service_irq(struct intel_dp *intel_dp)
 {
        struct intel_display *display = to_intel_display(intel_dp);
@@ -5813,12 +5818,15 @@ static bool intel_dp_check_link_service_irq(struct 
intel_dp *intel_dp)
                return false;
 
        if (drm_dp_dpcd_readb(&intel_dp->aux,
-                             DP_LINK_SERVICE_IRQ_VECTOR_ESI0, &val) != 1 || 
!val)
+                             DP_LINK_SERVICE_IRQ_VECTOR_ESI0, &val) != 1)
+               return true;
+
+       if (!val)
                return false;
 
        if (drm_dp_dpcd_writeb(&intel_dp->aux,
                               DP_LINK_SERVICE_IRQ_VECTOR_ESI0, val) != 1)
-               return false;
+               return true;
 
        if (val & RX_CAP_CHANGED)
                reprobe_needed = true;
-- 
2.49.1

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