drm/radeon: 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.

This is somewhat rare on most cards (depending on what angle you plug
the DVI connector in), but on some cards it happens constantly. The
Radeon R5 on the machine used for testing this patch for instance, runs
into this issue just about every time I try to hotplug a DVI monitor and
as a result hotplugging almost never works.

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.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Lyude <cpaul@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/cik.c

@@ -8472,7 +8472,7 @@ restart_ih:
 	if (queue_dp)
 		schedule_work(&rdev->dp_work);
 	if (queue_hotplug)
-		schedule_work(&rdev->hotplug_work);
+		schedule_delayed_work(&rdev->hotplug_work, 0);
 	if (queue_reset) {
 		rdev->needs_reset = true;
 		wake_up_all(&rdev->fence_queue);

drivers/gpu/drm/radeon/evergreen.c

@@ -5344,7 +5344,7 @@ restart_ih:
 	if (queue_dp)
 		schedule_work(&rdev->dp_work);
 	if (queue_hotplug)
-		schedule_work(&rdev->hotplug_work);
+		schedule_delayed_work(&rdev->hotplug_work, 0);
 	if (queue_hdmi)
 		schedule_work(&rdev->audio_work);
 	if (queue_thermal && rdev->pm.dpm_enabled)

drivers/gpu/drm/radeon/r100.c

@@ -806,7 +806,7 @@ int r100_irq_process(struct radeon_device *rdev)
 		status = r100_irq_ack(rdev);
 	}
 	if (queue_hotplug)
-		schedule_work(&rdev->hotplug_work);
+		schedule_delayed_work(&rdev->hotplug_work, 0);
 	if (rdev->msi_enabled) {
 		switch (rdev->family) {
 		case CHIP_RS400:

drivers/gpu/drm/radeon/r600.c

@@ -4276,7 +4276,7 @@ restart_ih:
 		WREG32(IH_RB_RPTR, rptr);
 	}
 	if (queue_hotplug)
-		schedule_work(&rdev->hotplug_work);
+		schedule_delayed_work(&rdev->hotplug_work, 0);
 	if (queue_hdmi)
 		schedule_work(&rdev->audio_work);
 	if (queue_thermal && rdev->pm.dpm_enabled)

drivers/gpu/drm/radeon/radeon.h

@@ -2414,7 +2414,7 @@ struct radeon_device {
 	struct r600_ih ih; /* r6/700 interrupt ring */
 	struct radeon_rlc rlc;
 	struct radeon_mec mec;
-	struct work_struct hotplug_work;
+	struct delayed_work hotplug_work;
 	struct work_struct dp_work;
 	struct work_struct audio_work;
 	int num_crtc; /* number of crtcs */

drivers/gpu/drm/radeon/radeon_connectors.c

@@ -1234,13 +1234,32 @@ radeon_dvi_detect(struct drm_connector *connector, bool force)
 	if (r < 0)
 		return connector_status_disconnected;
 
+	if (radeon_connector->detected_hpd_without_ddc) {
+		force = true;
+		radeon_connector->detected_hpd_without_ddc = false;
+	}
+
 	if (!force && radeon_check_hpd_status_unchanged(connector)) {
 		ret = connector->status;
 		goto exit;
 	}
 
-	if (radeon_connector->ddc_bus)
+	if (radeon_connector->ddc_bus) {
 		dret = radeon_ddc_probe(radeon_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 &&
+		    connector->status != connector_status_connected) {
+			DRM_DEBUG_KMS("hpd detected without ddc, retrying in 1 second\n");
+			radeon_connector->detected_hpd_without_ddc = true;
+			schedule_delayed_work(&rdev->hotplug_work,
+					      msecs_to_jiffies(1000));
+			goto exit;
+		}
+	}
 	if (dret) {
 		radeon_connector->detected_by_load = false;
 		radeon_connector_free_edid(connector);

drivers/gpu/drm/radeon/radeon_irq_kms.c

@@ -74,7 +74,7 @@ irqreturn_t radeon_driver_irq_handler_kms(int irq, void *arg)
 static void radeon_hotplug_work_func(struct work_struct *work)
 {
 	struct radeon_device *rdev = container_of(work, struct radeon_device,
-						  hotplug_work);
+						  hotplug_work.work);
 	struct drm_device *dev = rdev->ddev;
 	struct drm_mode_config *mode_config = &dev->mode_config;
 	struct drm_connector *connector;
@@ -302,7 +302,7 @@ int radeon_irq_kms_init(struct radeon_device *rdev)
 		}
 	}
 
-	INIT_WORK(&rdev->hotplug_work, radeon_hotplug_work_func);
+	INIT_DELAYED_WORK(&rdev->hotplug_work, radeon_hotplug_work_func);
 	INIT_WORK(&rdev->dp_work, radeon_dp_work_func);
 	INIT_WORK(&rdev->audio_work, r600_audio_update_hdmi);
 
@@ -310,7 +310,7 @@ int radeon_irq_kms_init(struct radeon_device *rdev)
 	r = drm_irq_install(rdev->ddev, rdev->ddev->pdev->irq);
 	if (r) {
 		rdev->irq.installed = false;
-		flush_work(&rdev->hotplug_work);
+		flush_delayed_work(&rdev->hotplug_work);
 		return r;
 	}
 
@@ -333,7 +333,7 @@ void radeon_irq_kms_fini(struct radeon_device *rdev)
 		rdev->irq.installed = false;
 		if (rdev->msi_enabled)
 			pci_disable_msi(rdev->pdev);
-		flush_work(&rdev->hotplug_work);
+		flush_delayed_work(&rdev->hotplug_work);
 	}
 }
 

drivers/gpu/drm/radeon/radeon_mode.h

@@ -553,6 +553,7 @@ struct radeon_connector {
 	void *con_priv;
 	bool dac_load_detect;
 	bool detected_by_load; /* if the connection status was determined by load */
+	bool detected_hpd_without_ddc; /* if an HPD signal was detected on DVI, but ddc probing failed */
 	uint16_t connector_object_id;
 	struct radeon_hpd hpd;
 	struct radeon_router router;

drivers/gpu/drm/radeon/rs600.c

@@ -813,7 +813,7 @@ int rs600_irq_process(struct radeon_device *rdev)
 		status = rs600_irq_ack(rdev);
 	}
 	if (queue_hotplug)
-		schedule_work(&rdev->hotplug_work);
+		schedule_delayed_work(&rdev->hotplug_work, 0);
 	if (queue_hdmi)
 		schedule_work(&rdev->audio_work);
 	if (rdev->msi_enabled) {

drivers/gpu/drm/radeon/si.c

@@ -6848,7 +6848,7 @@ restart_ih:
 	if (queue_dp)
 		schedule_work(&rdev->dp_work);
 	if (queue_hotplug)
-		schedule_work(&rdev->hotplug_work);
+		schedule_delayed_work(&rdev->hotplug_work, 0);
 	if (queue_thermal && rdev->pm.dpm_enabled)
 		schedule_work(&rdev->pm.dpm.thermal.work);
 	rdev->ih.rptr = rptr;