[PATCH v2 12/12] drm/amd/display: Move dc_state copy in commit_tail after dc_commit_state

[Harry Wentland]

On 2022-10-18 08:28, Rodrigo Siqueira wrote:
> From: Aurabindo Pillai <aurabindo.pillai at amd.com>
> 
> The SubVP feature introduces a new mechanism named phantom streams,
> which can be summed up as a fake stream used to calculate the required
> parameters for handing the cache request and cache reading for a small
> portion of the framebuffer used in the sub-viewport. With the new commit
> sequence, we do not want the state to be copied before the call to
> dc_commit_state() since this leaks the phantom streams into new state.
> To address this issue, this commit move the dc state copy right after
> the dc_commit_state() call.
> 
> Signed-off-by: Aurabindo Pillai <aurabindo.pillai at amd.com>
> ---
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c   | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 63f076a46260..17a9108f8186 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -7999,15 +7999,8 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
>  	drm_atomic_helper_update_legacy_modeset_state(dev, state);
>  
>  	dm_state = dm_atomic_get_new_state(state);
> -	if (dm_state && dm_state->context) {
> +	if (dm_state && dm_state->context)
>  		dc_state = dm_state->context;
> -	} else {
> -		/* No state changes, retain current state. */
> -		dc_state_temp = dc_create_state(dm->dc);
> -		ASSERT(dc_state_temp);
> -		dc_state = dc_state_temp;
> -		dc_resource_state_copy_construct_current(dm->dc, dc_state);
> -	}
>  
>  	for_each_oldnew_crtc_in_state (state, crtc, old_crtc_state,
>  				       new_crtc_state, i) {
> @@ -8127,6 +8120,14 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
>  		mutex_unlock(&dm->dc_lock);
>  	}
>  
> +	if (dc_state == NULL) {
> +		/* No state changes, retain current state. */
> +		dc_state_temp = dc_create_state(dm->dc);
> +		ASSERT(dc_state_temp);
> +		dc_state = dc_state_temp;
> +		dc_resource_state_copy_construct_current(dm->dc, dc_state);
> +	}

Should this simply be dropped with the new sequence since both
dc_commit_streams and update_planes_and_stream_state (on FULL update)
create a new state?

I wonder if moving this will impact the old sequence.

Harry

> +
>  	for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
>  		struct amdgpu_crtc *acrtc = to_amdgpu_crtc(crtc);
>