Re: [PATCH] Revert "drm/amdgpu: Implement insert_end for VCE 3"

[David Rosca <david.rosca@amd.com>]

On 8/14/26 17:08, Alex Deucher wrote:
> On Fri, Aug 14, 2026 at 11:05 AM David Rosca <david.rosca@amd.com> wrote:
>> This doesn't solve the issue, VCE still hangs in some cases.
>>
>> 4959138b6461 ("drm/amdgpu: handle GDS and SPM without a VM fence")
>> fixes the regression, originally introduced in
>> 83a8dee2bdfb ("drm/amdgpu: always emit the job vm fence").
> This doesn't make sense to me.  GDS and SPM are not supported on VCN
> in the first place so they would never be emitted for VCN.

The issue was the extra fence when only pipeline sync was needed.
With 4959138b6461 ("drm/amdgpu: handle GDS and SPM without a VM fence") 
the fence is not emitted in that case.

David

>
> Alex
>
>> This reverts commit 7591335141a06d5b176510054576d9c64519f348.
>>
>> Signed-off-by: David Rosca <david.rosca@amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/vce_v3_0.c | 26 ++++----------------------
>>   1 file changed, 4 insertions(+), 22 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/vce_v3_0.c b/drivers/gpu/drm/amd/amdgpu/vce_v3_0.c
>> index a9497e2e07f7..9f4e88440c0a 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/vce_v3_0.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/vce_v3_0.c
>> @@ -809,23 +809,6 @@ static void vce_v3_0_ring_emit_ib(struct amdgpu_ring *ring,
>>          amdgpu_ring_write(ring, ib->length_dw);
>>   }
>>
>> -static void vce_v3_0_ring_emit_fence(struct amdgpu_ring *ring, u64 addr,
>> -                       u64 seq, unsigned flags)
>> -{
>> -       WARN_ON(flags & AMDGPU_FENCE_FLAG_64BIT);
>> -
>> -       amdgpu_ring_write(ring, VCE_CMD_FENCE);
>> -       amdgpu_ring_write(ring, addr);
>> -       amdgpu_ring_write(ring, upper_32_bits(addr));
>> -       amdgpu_ring_write(ring, seq);
>> -       amdgpu_ring_write(ring, VCE_CMD_TRAP);
>> -}
>> -
>> -static void vce_v3_0_ring_insert_end(struct amdgpu_ring *ring)
>> -{
>> -       amdgpu_ring_write(ring, VCE_CMD_END);
>> -}
>> -
>>   static void vce_v3_0_emit_vm_flush(struct amdgpu_ring *ring,
>>                                     unsigned int vmid, uint64_t pd_addr)
>>   {
>> @@ -835,6 +818,7 @@ static void vce_v3_0_emit_vm_flush(struct amdgpu_ring *ring,
>>
>>          amdgpu_ring_write(ring, VCE_CMD_FLUSH_TLB);
>>          amdgpu_ring_write(ring, vmid);
>> +       amdgpu_ring_write(ring, VCE_CMD_END);
>>   }
>>
>>   static void vce_v3_0_emit_pipeline_sync(struct amdgpu_ring *ring)
>> @@ -900,19 +884,17 @@ static const struct amdgpu_ring_funcs vce_v3_0_ring_vm_funcs = {
>>          .set_wptr = vce_v3_0_ring_set_wptr,
>>          .patch_cs_in_place = amdgpu_vce_ring_parse_cs_vm,
>>          .emit_frame_size =
>> -               5 + /* vce_v3_0_emit_vm_flush */
>> +               6 + /* vce_v3_0_emit_vm_flush */
>>                  4 + /* vce_v3_0_emit_pipeline_sync */
>> -               5 + 5 + /* vce_v3_0_ring_emit_fence x2 vm fence */
>> -               1, /* vce_v3_0_ring_insert_end */
>> +               6 + 6, /* amdgpu_vce_ring_emit_fence x2 vm fence */
>>          .emit_ib_size = 5, /* vce_v3_0_ring_emit_ib */
>>          .emit_ib = vce_v3_0_ring_emit_ib,
>>          .emit_vm_flush = vce_v3_0_emit_vm_flush,
>>          .emit_pipeline_sync = vce_v3_0_emit_pipeline_sync,
>> -       .emit_fence = vce_v3_0_ring_emit_fence,
>> +       .emit_fence = amdgpu_vce_ring_emit_fence,
>>          .test_ring = amdgpu_vce_ring_test_ring,
>>          .test_ib = amdgpu_vce_ring_test_ib,
>>          .insert_nop = amdgpu_ring_insert_nop,
>> -       .insert_end = vce_v3_0_ring_insert_end,
>>          .pad_ib = amdgpu_ring_generic_pad_ib,
>>          .begin_use = amdgpu_vce_ring_begin_use,
>>          .end_use = amdgpu_vce_ring_end_use,
>> --
>> 2.43.0
>>