[PATCH 9/9] drm/amdgpu/uvd4.2: Don't initialize UVD 4.2 when DPM is disabled

[Timur Kristóf]

UVD 4.2 doesn't work at all when DPM is disabled because
the SMU is responsible for ungating it. So, Linux fails
to boot with CIK GPUs when using the amdgpu.dpm=0 parameter.

Fix this by returning -ENOENT from uvd_v4_2_early_init()
when amdgpu_dpm isn't enabled.

Note: amdgpu.dpm=0 is often suggested as a workaround
for issues and is useful for debugging.

Fixes: a2e73f56fa62 ("drm/amdgpu: Add support for CIK parts")
Signed-off-by: Timur Kristóf <timur.kris...@gmail.com>
---
 drivers/gpu/drm/amd/amdgpu/uvd_v4_2.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/uvd_v4_2.c 
b/drivers/gpu/drm/amd/amdgpu/uvd_v4_2.c
index 73ce3d211ed64..8a9ba2276275c 100644
--- a/drivers/gpu/drm/amd/amdgpu/uvd_v4_2.c
+++ b/drivers/gpu/drm/amd/amdgpu/uvd_v4_2.c
@@ -93,6 +93,11 @@ static void uvd_v4_2_ring_set_wptr(struct amdgpu_ring *ring)
 static int uvd_v4_2_early_init(struct amdgpu_ip_block *ip_block)
 {
        struct amdgpu_device *adev = ip_block->adev;
+
+       /* UVD doesn't work without DPM, it needs DPM to ungate it. */
+       if (!amdgpu_dpm)
+               return -ENOENT;
+
        adev->uvd.num_uvd_inst = 1;
 
        uvd_v4_2_set_ring_funcs(adev);
-- 
2.53.0