Re: [PATCH v3 1/3] drm/i915/psr: Set plane id bit in crtc_state->async_flip_planes for PSR

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Dec 01, 2025 at 03:24:55PM +0200, Jouni Högander wrote:
> Currently plane id bit is set in crtc_state->async_flip_planes only when
> async flip toggle workaround is needed. We want to utilize
> crtc_state->async_flip_planes further in Selective Fetch calculation.
> 
> Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_plane.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_plane.c b/drivers/gpu/drm/i915/display/intel_plane.c
> index 7b7619d59251..de0a69c55582 100644
> --- a/drivers/gpu/drm/i915/display/intel_plane.c
> +++ b/drivers/gpu/drm/i915/display/intel_plane.c
> @@ -603,8 +603,7 @@ static int intel_plane_atomic_calc_changes(const struct intel_crtc_state *old_cr
>  	if (intel_plane_do_async_flip(plane, old_crtc_state, new_crtc_state)) {
>  		new_crtc_state->do_async_flip = true;
>  		new_crtc_state->async_flip_planes |= BIT(plane->id);
> -	} else if (plane->need_async_flip_toggle_wa &&
> -		   new_crtc_state->uapi.async_flip) {
> +	} else if (new_crtc_state->uapi.async_flip) {

I'd get rid of the if-else construct here now, and just do something
like:

if (intel_plane_do_async_flip(...))
	new_crtc_state->do_async_flip = true;

if (new_crtc_state->uapi.async_flip) {
	/* ... */
	new_crtc_state->async_flip_planes |= BIT(plane->id);
}

We should probably also move the plane->async_flip check
out from intel_plane_do_async_flip() and just make it a
drm_WARN_ON(..., uapi.async_flip && !plane->async_flip).
But that's probably better left for a separate patch.

>  		/*
>  		 * On platforms with double buffered async flip bit we
>  		 * set the bit already one frame early during the sync
> @@ -612,6 +611,13 @@ static int intel_plane_atomic_calc_changes(const struct intel_crtc_state *old_cr
>  		 * hardware will therefore be ready to perform a real
>  		 * async flip during the next commit, without having
>  		 * to wait yet another frame for the bit to latch.
> +		 *
> +		 * async_flip_planes bitmask is also used by selective
> +		 * fetch calculation to continue full frame updates as
> +		 * long as there may be pending async flip on any
> +		 * plane which is part of selective
> +		 * update. I.e. old_crtc_state->async_flip_planes &
> +		 * BIT(<plane in su area>->id).
>  		 */
>  		new_crtc_state->async_flip_planes |= BIT(plane->id);
>  	}
> -- 
> 2.43.0

-- 
Ville Syrjälä
Intel