drm/amdgpu: Handle irqs only based on irq ring, not irq status regs.

This is a translation of the patch ...
"drm/radeon: Handle irqs only based on irq ring, not irq status regs."
... for the vblank irq handling, to fix the same problem described
in that patch on the new driver.

Only compile tested due to lack of suitable hw.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
CC: Michel Dänzer <michel.daenzer@amd.com>
CC: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/dce_v10_0.c

@@ -3403,19 +3403,25 @@ static int dce_v10_0_crtc_irq(struct amdgpu_device *adev,
 
 	switch (entry->src_data) {
 	case 0: /* vblank */
-		if (disp_int & interrupt_status_offsets[crtc].vblank) {
+		if (disp_int & interrupt_status_offsets[crtc].vblank)
 			dce_v10_0_crtc_vblank_int_ack(adev, crtc);
+		else
+			DRM_DEBUG("IH: IH event w/o asserted irq bit?\n");
+
 		if (amdgpu_irq_enabled(adev, source, irq_type)) {
 			drm_handle_vblank(adev->ddev, crtc);
 		}
 		DRM_DEBUG("IH: D%d vblank\n", crtc + 1);
-		}
+
 		break;
 	case 1: /* vline */
-		if (disp_int & interrupt_status_offsets[crtc].vline) {
+		if (disp_int & interrupt_status_offsets[crtc].vline)
 			dce_v10_0_crtc_vline_int_ack(adev, crtc);
+		else
+			DRM_DEBUG("IH: IH event w/o asserted irq bit?\n");
+
 		DRM_DEBUG("IH: D%d vline\n", crtc + 1);
-		}
+
 		break;
 	default:
 		DRM_DEBUG("Unhandled interrupt: %d %d\n", entry->src_id, entry->src_data);

drivers/gpu/drm/amd/amdgpu/dce_v11_0.c

@@ -3402,19 +3402,25 @@ static int dce_v11_0_crtc_irq(struct amdgpu_device *adev,
 
 	switch (entry->src_data) {
 	case 0: /* vblank */
-		if (disp_int & interrupt_status_offsets[crtc].vblank) {
+		if (disp_int & interrupt_status_offsets[crtc].vblank)
 			dce_v11_0_crtc_vblank_int_ack(adev, crtc);
+		else
+			DRM_DEBUG("IH: IH event w/o asserted irq bit?\n");
+
 		if (amdgpu_irq_enabled(adev, source, irq_type)) {
 			drm_handle_vblank(adev->ddev, crtc);
 		}
 		DRM_DEBUG("IH: D%d vblank\n", crtc + 1);
-		}
+
 		break;
 	case 1: /* vline */
-		if (disp_int & interrupt_status_offsets[crtc].vline) {
+		if (disp_int & interrupt_status_offsets[crtc].vline)
 			dce_v11_0_crtc_vline_int_ack(adev, crtc);
+		else
+			DRM_DEBUG("IH: IH event w/o asserted irq bit?\n");
+
 		DRM_DEBUG("IH: D%d vline\n", crtc + 1);
-		}
+
 		break;
 	default:
 		DRM_DEBUG("Unhandled interrupt: %d %d\n", entry->src_id, entry->src_data);

drivers/gpu/drm/amd/amdgpu/dce_v8_0.c

@@ -3237,19 +3237,25 @@ static int dce_v8_0_crtc_irq(struct amdgpu_device *adev,
 
 	switch (entry->src_data) {
 	case 0: /* vblank */
-		if (disp_int & interrupt_status_offsets[crtc].vblank) {
+		if (disp_int & interrupt_status_offsets[crtc].vblank)
 			WREG32(mmLB_VBLANK_STATUS + crtc_offsets[crtc], LB_VBLANK_STATUS__VBLANK_ACK_MASK);
+		else
+			DRM_DEBUG("IH: IH event w/o asserted irq bit?\n");
+
 		if (amdgpu_irq_enabled(adev, source, irq_type)) {
 			drm_handle_vblank(adev->ddev, crtc);
 		}
 		DRM_DEBUG("IH: D%d vblank\n", crtc + 1);
-		}
+
 		break;
 	case 1: /* vline */
-		if (disp_int & interrupt_status_offsets[crtc].vline) {
+		if (disp_int & interrupt_status_offsets[crtc].vline)
 			WREG32(mmLB_VLINE_STATUS + crtc_offsets[crtc], LB_VLINE_STATUS__VLINE_ACK_MASK);
+		else
+			DRM_DEBUG("IH: IH event w/o asserted irq bit?\n");
+
 		DRM_DEBUG("IH: D%d vline\n", crtc + 1);
-		}
+
 		break;
 	default:
 		DRM_DEBUG("Unhandled interrupt: %d %d\n", entry->src_id, entry->src_data);