Re: [Intel-gfx] [PATCH] drm/i915/display: Exit PSR when doing async flips

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Fri, Oct 29, 2021 at 05:18:01PM -0700, José Roberto de Souza wrote:
> Changing the buffer in the middle of the scanout then entering an
> period of flip idleness will cause part of the previous buffer being
> diplayed to user when PSR is enabled.
> 
> So here disabling and scheduling activation after a few milliseconds
> when async flip is enabled in the state.
> 
> The async flip check that we had in PSR compute is not executed at
> every flip so it was not doing anything useful and is also being
> dropped here.
> 
> Cc: Karthik B S <karthik.b.s@intel.com>
> Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_psr.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> index 9d589d471e335..d1301e2729553 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -731,12 +731,6 @@ static bool intel_psr2_sel_fetch_config_valid(struct intel_dp *intel_dp,
>  		return false;
>  	}
>  
> -	if (crtc_state->uapi.async_flip) {
> -		drm_dbg_kms(&dev_priv->drm,
> -			    "PSR2 sel fetch not enabled, async flip enabled\n");
> -		return false;
> -	}
> -
>  	/* Wa_14010254185 Wa_14010103792 */
>  	if (IS_TGL_DISPLAY_STEP(dev_priv, STEP_A0, STEP_C0)) {
>  		drm_dbg_kms(&dev_priv->drm,
> @@ -1780,6 +1774,11 @@ void intel_psr_pre_plane_update(struct intel_atomic_state *state,
>  		if (psr->enabled && needs_to_disable)
>  			intel_psr_disable_locked(intel_dp);
>  
> +		if (psr->enabled && crtc_state->uapi.async_flip) {
> +			intel_psr_exit(intel_dp);
> +			schedule_work(&intel_dp->psr.work);

wouldn't it be better(safer?) to reschedule it back in a later stage?

> +		}
> +
>  		mutex_unlock(&psr->lock);
>  	}
>  }
> -- 
> 2.33.1
>