drm/amdgpu: expose benchmarks via debugfs

They provide a nice smoke test of transfer performance
using SDMA.  Allow the user to run these at runtime
rather than only at init time.

v2: fix permissions (Alex)
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1362,6 +1362,25 @@ static int amdgpu_debugfs_evict_gtt(void *data, u64 *val)
 	return 0;
 }
 
+static int amdgpu_debugfs_benchmark(void *data, u64 val)
+{
+	struct amdgpu_device *adev = (struct amdgpu_device *)data;
+	struct drm_device *dev = adev_to_drm(adev);
+	int r;
+
+	r = pm_runtime_get_sync(dev->dev);
+	if (r < 0) {
+		pm_runtime_put_autosuspend(dev->dev);
+		return r;
+	}
+
+	r = amdgpu_benchmark(adev, val);
+
+	pm_runtime_mark_last_busy(dev->dev);
+	pm_runtime_put_autosuspend(dev->dev);
+
+	return r;
+}
 
 static int amdgpu_debugfs_vm_info_show(struct seq_file *m, void *unused)
 {
@@ -1398,6 +1417,8 @@ DEFINE_DEBUGFS_ATTRIBUTE(amdgpu_evict_vram_fops, amdgpu_debugfs_evict_vram,
 			 NULL, "%lld\n");
 DEFINE_DEBUGFS_ATTRIBUTE(amdgpu_evict_gtt_fops, amdgpu_debugfs_evict_gtt,
 			 NULL, "%lld\n");
+DEFINE_DEBUGFS_ATTRIBUTE(amdgpu_benchmark_fops, NULL, amdgpu_debugfs_benchmark,
+			 "%lld\n");
 
 static void amdgpu_ib_preempt_fences_swap(struct amdgpu_ring *ring,
 					  struct dma_fence **fences)
@@ -1683,6 +1704,8 @@ int amdgpu_debugfs_init(struct amdgpu_device *adev)
 			    &amdgpu_debugfs_test_ib_fops);
 	debugfs_create_file("amdgpu_vm_info", 0444, root, adev,
 			    &amdgpu_debugfs_vm_info_fops);
+	debugfs_create_file("amdgpu_benchmark", 0200, root, adev,
+			    &amdgpu_benchmark_fops);
 
 	adev->debugfs_vbios_blob.data = adev->bios;
 	adev->debugfs_vbios_blob.size = adev->bios_size;