Re: [PATCH] drm/amdgpu/vcn: fix idle work handler for VCN 2.5

[Boyuan Zhang <Boyuan.Zhang@xxxxxxx>]

On 2025-03-04 11:22, Alex Deucher wrote:
> VCN 2.5 uses the PG callback to enable VCN DPM which is
> a global state.  As such, we need to make sure all instances
> are in the same state.
>
> v2: switch to a ref count (Lijo)
>
> Fixes: 4ce4fe27205c ("drm/amdgpu/vcn: use per instance callbacks for idle work handler")
> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h |  4 +++
>   drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c   | 41 +++++++++++++++++++------
>   2 files changed, 36 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h
> index 26c9c2d90f455..3bc4fe4aeb481 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vcn.h
> @@ -358,6 +358,10 @@ struct amdgpu_vcn {
>   
>   	bool			per_inst_fw;
>   	unsigned		fw_version;
> +	/* VCN 2.5 global PG handling */
> +	struct mutex		global_pg_lock;
> +	unsigned int		global_pg_count;
> +	enum amd_powergating_state global_pg_state;
>   };
>   
>   struct amdgpu_fw_shared_rb_ptrs_struct {
> diff --git a/drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c b/drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c
> index dff1a88590363..972f0842ea47b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c
> +++ b/drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c
> @@ -172,6 +172,8 @@ static int vcn_v2_5_sw_init(struct amdgpu_ip_block *ip_block)
>   	uint32_t *ptr;
>   	struct amdgpu_device *adev = ip_block->adev;
>   
> +	mutex_init(&adev->vcn.global_pg_lock);
> +
>   	for (j = 0; j < adev->vcn.num_vcn_inst; j++) {
>   		volatile struct amdgpu_fw_shared *fw_shared;
>   
> @@ -1853,21 +1855,42 @@ static int vcn_v2_5_set_pg_state(struct amdgpu_vcn_inst *vinst,
>   				 enum amd_powergating_state state)
>   {
>   	struct amdgpu_device *adev = vinst->adev;
> -	int ret;
> +	struct amdgpu_vcn_inst *v;
> +	int ret = 0, i;
>   
>   	if (amdgpu_sriov_vf(adev))
>   		return 0;
>   
> -	if (state == vinst->cur_state)
> -		return 0;
> +	mutex_lock(&adev->vcn.global_pg_lock);
> +	if (state == AMD_PG_STATE_GATE) {
> +		if (adev->vcn.global_pg_count == 0)
> +			goto unlock;
> +		adev->vcn.global_pg_count--;
> +		if (adev->vcn.global_pg_count == 0 &&
> +		    adev->vcn.global_pg_state == AMD_PG_STATE_UNGATE) {
> +			for (i = 0; i < adev->vcn.num_vcn_inst; ++i) {
> +				v = &adev->vcn.inst[i];
> +
> +				ret = vcn_v2_5_stop(v);
> +			}
> +			adev->vcn.global_pg_state = AMD_PG_STATE_GATE;
> +		}
> +	} else {
> +		if (adev->vcn.global_pg_count == 0 &&
> +		    adev->vcn.global_pg_state == AMD_PG_STATE_GATE) {
> +			for (i = 0; i < adev->vcn.num_vcn_inst; ++i) {
> +				v = &adev->vcn.inst[i];
>   
> -	if (state == AMD_PG_STATE_GATE)
> -		ret = vcn_v2_5_stop(vinst);
> -	else
> -		ret = vcn_v2_5_start(vinst);
> +				ret = vcn_v2_5_start(v);
> +			}
> +			adev->vcn.global_pg_state = AMD_PG_STATE_UNGATE;
> +		}
> +		adev->vcn.global_pg_count++;
> +	}
>   
> -	if (!ret)
> -		vinst->cur_state = state;
> +unlock:
> +	vinst->cur_state = state;


I guess we don't need to bother this per instant (vinst->cur_state) at 
all in this case? Other than this, this patch is

Reviewed-by: Boyuan Zhang <Boyuan.Zhang@xxxxxxx>


> +	mutex_unlock(&adev->vcn.global_pg_lock);
>   
>   	return ret;
>   }