drm/amdgpu: Retry DDC probing on DVI on failure if we got an HPD interrupt

HPD signals on DVI ports can be fired off before the pins required for
DDC probing actually make contact, due to the pins for HPD making
contact first. This results in a HPD signal being asserted but DDC
probing failing, resulting in hotplugging occasionally failing.

Rescheduling the hotplug work for a second when we run into an HPD
signal with a failing DDC probe usually gives enough time for the rest
of the connector's pins to make contact, and fixes this issue.

Signed-off-by: xurui <xurui@kylinos.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 21 insertions, 1 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
index 2ebbc6382a06..d2abd334b1b5 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
@@ -996,13 +996,33 @@ amdgpu_connector_dvi_detect(struct drm_connector *connector, bool force)
 		}
 	}
 
+	if (amdgpu_connector->detected_hpd_without_ddc) {
+		force = true;
+		amdgpu_connector->detected_hpd_without_ddc = false;
+	}
+
 	if (!force && amdgpu_connector_check_hpd_status_unchanged(connector)) {
 		ret = connector->status;
 		goto exit;
 	}
 
-	if (amdgpu_connector->ddc_bus)
+	if (amdgpu_connector->ddc_bus) {
 		dret = amdgpu_display_ddc_probe(amdgpu_connector, false);
+
+		/* Sometimes the pins required for the DDC probe on DVI
+		 * connectors don't make contact at the same time that the ones
+		 * for HPD do. If the DDC probe fails even though we had an HPD
+		 * signal, try again later
+		 */
+		if (!dret && !force &&
+		    amdgpu_display_hpd_sense(adev, amdgpu_connector->hpd.hpd)) {
+			DRM_DEBUG_KMS("hpd detected without ddc, retrying in 1 second\n");
+			amdgpu_connector->detected_hpd_without_ddc = true;
+			schedule_delayed_work(&adev->hotplug_work,
+					      msecs_to_jiffies(1000));
+			goto exit;
+		}
+	}
 	if (dret) {
 		amdgpu_connector->detected_by_load = false;
 		amdgpu_connector_free_edid(connector);