drm/amdgpu: Fix dead lock issue for vblank

Always start vblank timer, but only calls vblank function
when vblank is enabled.

This is used to fix the dead lock issue.
When drm_crtc_vblank_off want to disable vblank,
it first get event_lock, and then call hrtimer_cancel,
but hrtimer_cancel want to wait timer handler function finished.
Timer handler also want to aquire event_lock in drm_handle_vblank.
Signed-off-by: Emily.Deng <Emily.Deng@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/dce_virtual.c

@@ -47,6 +47,9 @@ static void dce_virtual_set_display_funcs(struct amdgpu_device *adev);
 static void dce_virtual_set_irq_funcs(struct amdgpu_device *adev);
 static int dce_virtual_connector_encoder_init(struct amdgpu_device *adev,
 					      int index);
+static int dce_virtual_pageflip(struct amdgpu_device *adev,
+				unsigned crtc_id);
+static enum hrtimer_restart dce_virtual_vblank_timer_handle(struct hrtimer *vblank_timer);
 static void dce_virtual_set_crtc_vblank_interrupt_state(struct amdgpu_device *adev,
 							int crtc,
 							enum amdgpu_interrupt_state state);
@@ -247,6 +250,11 @@ static int dce_virtual_crtc_init(struct amdgpu_device *adev, int index)
 	amdgpu_crtc->vsync_timer_enabled = AMDGPU_IRQ_STATE_DISABLE;
 	drm_crtc_helper_add(&amdgpu_crtc->base, &dce_virtual_crtc_helper_funcs);
 
+	hrtimer_init(&amdgpu_crtc->vblank_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	hrtimer_set_expires(&amdgpu_crtc->vblank_timer, DCE_VIRTUAL_VBLANK_PERIOD);
+	amdgpu_crtc->vblank_timer.function = dce_virtual_vblank_timer_handle;
+	hrtimer_start(&amdgpu_crtc->vblank_timer,
+		      DCE_VIRTUAL_VBLANK_PERIOD, HRTIMER_MODE_REL);
 	return 0;
 }
 
@@ -476,7 +484,7 @@ static int dce_virtual_hw_fini(void *handle)
 
 	for (i = 0; i<adev->mode_info.num_crtc; i++)
 		if (adev->mode_info.crtcs[i])
-			dce_virtual_set_crtc_vblank_interrupt_state(adev, i, AMDGPU_IRQ_STATE_DISABLE);
+			hrtimer_cancel(&adev->mode_info.crtcs[i]->vblank_timer);
 
 	return 0;
 }
@@ -698,9 +706,15 @@ static enum hrtimer_restart dce_virtual_vblank_timer_handle(struct hrtimer *vbla
 						       struct amdgpu_crtc, vblank_timer);
 	struct drm_device *ddev = amdgpu_crtc->base.dev;
 	struct amdgpu_device *adev = drm_to_adev(ddev);
+	struct amdgpu_irq_src *source = adev->irq.client[AMDGPU_IRQ_CLIENTID_LEGACY].sources
+		[VISLANDS30_IV_SRCID_SMU_DISP_TIMER2_TRIGGER];
+	int irq_type = amdgpu_display_crtc_idx_to_irq_type(adev,
+						amdgpu_crtc->crtc_id);
 
+	if (amdgpu_irq_enabled(adev, source, irq_type)) {
 		drm_handle_vblank(ddev, amdgpu_crtc->crtc_id);
 		dce_virtual_pageflip(adev, amdgpu_crtc->crtc_id);
+	}
 	hrtimer_start(vblank_timer, DCE_VIRTUAL_VBLANK_PERIOD,
 		      HRTIMER_MODE_REL);
 
@@ -716,21 +730,6 @@ static void dce_virtual_set_crtc_vblank_interrupt_state(struct amdgpu_device *ad
 		return;
 	}
 
-	if (state && !adev->mode_info.crtcs[crtc]->vsync_timer_enabled) {
-		DRM_DEBUG("Enable software vsync timer\n");
-		hrtimer_init(&adev->mode_info.crtcs[crtc]->vblank_timer,
-			     CLOCK_MONOTONIC, HRTIMER_MODE_REL);
-		hrtimer_set_expires(&adev->mode_info.crtcs[crtc]->vblank_timer,
-				    DCE_VIRTUAL_VBLANK_PERIOD);
-		adev->mode_info.crtcs[crtc]->vblank_timer.function =
-			dce_virtual_vblank_timer_handle;
-		hrtimer_start(&adev->mode_info.crtcs[crtc]->vblank_timer,
-			      DCE_VIRTUAL_VBLANK_PERIOD, HRTIMER_MODE_REL);
-	} else if (!state && adev->mode_info.crtcs[crtc]->vsync_timer_enabled) {
-		DRM_DEBUG("Disable software vsync timer\n");
-		hrtimer_cancel(&adev->mode_info.crtcs[crtc]->vblank_timer);
-	}
-
 	adev->mode_info.crtcs[crtc]->vsync_timer_enabled = state;
 	DRM_DEBUG("[FM]set crtc %d vblank interrupt state %d\n", crtc, state);
 }