drm/lima: always set page directory when switch vm

We need to flush TLB anyway before every task start, and the
page directory will be set to empty vm after suspend/resume,
so always set it to the task vm even no ctx switch happens.
Tested-by: Bhushan Shah <bshah@kde.org>
Reviewed-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200421133551.31481-5-yuq825@gmail.com

drivers/gpu/drm/lima/lima_mmu.c

@@ -113,8 +113,7 @@ void lima_mmu_switch_vm(struct lima_ip *ip, struct lima_vm *vm)
 			      LIMA_MMU_STATUS, v,
 			      v & LIMA_MMU_STATUS_STALL_ACTIVE);
 
-	if (vm)
-		mmu_write(LIMA_MMU_DTE_ADDR, vm->pd.dma);
+	mmu_write(LIMA_MMU_DTE_ADDR, vm->pd.dma);
 
 	/* flush the TLB */
 	mmu_write(LIMA_MMU_COMMAND, LIMA_MMU_COMMAND_ZAP_CACHE);

drivers/gpu/drm/lima/lima_sched.c

@@ -200,7 +200,6 @@ static struct dma_fence *lima_sched_run_job(struct drm_sched_job *job)
 	struct lima_sched_pipe *pipe = to_lima_pipe(job->sched);
 	struct lima_fence *fence;
 	struct dma_fence *ret;
-	struct lima_vm *vm = NULL, *last_vm = NULL;
 	int i;
 
 	/* after GPU reset */
@@ -239,21 +238,16 @@ static struct dma_fence *lima_sched_run_job(struct drm_sched_job *job)
 	for (i = 0; i < pipe->num_l2_cache; i++)
 		lima_l2_cache_flush(pipe->l2_cache[i]);
 
-	if (task->vm != pipe->current_vm) {
-		vm = lima_vm_get(task->vm);
-		last_vm = pipe->current_vm;
-		pipe->current_vm = task->vm;
-	}
+	lima_vm_put(pipe->current_vm);
+	pipe->current_vm = lima_vm_get(task->vm);
 
 	if (pipe->bcast_mmu)
-		lima_mmu_switch_vm(pipe->bcast_mmu, vm);
+		lima_mmu_switch_vm(pipe->bcast_mmu, pipe->current_vm);
 	else {
 		for (i = 0; i < pipe->num_mmu; i++)
-			lima_mmu_switch_vm(pipe->mmu[i], vm);
+			lima_mmu_switch_vm(pipe->mmu[i], pipe->current_vm);
 	}
 
-	lima_vm_put(last_vm);
-
 	trace_lima_task_run(task);
 
 	pipe->error = false;