drm/amdgpu/gmc10: don't touch gfxhub registers during S0ix

gfxhub registers are part of gfx IP and should not need to be
changed.  Doing so without disabling gfxoff can hang the gfx IP.

v2: add comments explaining why we can skip the interrupt
    control for S0i3
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c

@@ -78,12 +78,24 @@ gmc_v10_0_vm_fault_interrupt_state(struct amdgpu_device *adev,
 		/* MM HUB */
 		amdgpu_gmc_set_vm_fault_masks(adev, AMDGPU_MMHUB_0, false);
 		/* GFX HUB */
+		/* This works because this interrupt is only
+		 * enabled at init/resume and disabled in
+		 * fini/suspend, so the overall state doesn't
+		 * change over the course of suspend/resume.
+		 */
+		if (!adev->in_s0ix)
 			amdgpu_gmc_set_vm_fault_masks(adev, AMDGPU_GFXHUB_0, false);
 		break;
 	case AMDGPU_IRQ_STATE_ENABLE:
 		/* MM HUB */
 		amdgpu_gmc_set_vm_fault_masks(adev, AMDGPU_MMHUB_0, true);
 		/* GFX HUB */
+		/* This works because this interrupt is only
+		 * enabled at init/resume and disabled in
+		 * fini/suspend, so the overall state doesn't
+		 * change over the course of suspend/resume.
+		 */
+		if (!adev->in_s0ix)
 			amdgpu_gmc_set_vm_fault_masks(adev, AMDGPU_GFXHUB_0, true);
 		break;
 	default:
@@ -1061,9 +1073,12 @@ static int gmc_v10_0_gart_enable(struct amdgpu_device *adev)
 	}
 
 	amdgpu_gtt_mgr_recover(&adev->mman.gtt_mgr);
+
+	if (!adev->in_s0ix) {
 		r = adev->gfxhub.funcs->gart_enable(adev);
 		if (r)
 			return r;
+	}
 
 	r = adev->mmhub.funcs->gart_enable(adev);
 	if (r)
@@ -1077,9 +1092,11 @@ static int gmc_v10_0_gart_enable(struct amdgpu_device *adev)
 	value = (amdgpu_vm_fault_stop == AMDGPU_VM_FAULT_STOP_ALWAYS) ?
 		false : true;
 
+	if (!adev->in_s0ix)
 		adev->gfxhub.funcs->set_fault_enable_default(adev, value);
 	adev->mmhub.funcs->set_fault_enable_default(adev, value);
 	gmc_v10_0_flush_gpu_tlb(adev, 0, AMDGPU_MMHUB_0, 0);
+	if (!adev->in_s0ix)
 		gmc_v10_0_flush_gpu_tlb(adev, 0, AMDGPU_GFXHUB_0, 0);
 
 	DRM_INFO("PCIE GART of %uM enabled (table at 0x%016llX).\n",
@@ -1101,7 +1118,7 @@ static int gmc_v10_0_hw_init(void *handle)
 	 * harvestable groups in gc_utcl2 need to be programmed before any GFX block
 	 * register setup within GMC, or else system hang when harvesting SA.
 	 */
-	if (adev->gfxhub.funcs && adev->gfxhub.funcs->utcl2_harvest)
+	if (!adev->in_s0ix && adev->gfxhub.funcs && adev->gfxhub.funcs->utcl2_harvest)
 		adev->gfxhub.funcs->utcl2_harvest(adev);
 
 	r = gmc_v10_0_gart_enable(adev);
@@ -1129,6 +1146,7 @@ static int gmc_v10_0_hw_init(void *handle)
  */
 static void gmc_v10_0_gart_disable(struct amdgpu_device *adev)
 {
+	if (!adev->in_s0ix)
 		adev->gfxhub.funcs->gart_disable(adev);
 	adev->mmhub.funcs->gart_disable(adev);
 }