[Intel-gfx] [PATCH 2/7] drm/i915/display: Handle frontbuffer rendering when PSR2 selective fetch is enabled

[Gwan-gyeong Mun]

Looks good to me.
Reviewed-by: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>

On 9/23/21 10:46 PM, José Roberto de Souza wrote:
> CURSURFLIVE writes has no affect when PSR2 selective fetch is enabled,
> the right thing to do here would be calculate the damaged area and
> program PSR2 selective fetch registers properly during vblank but
> we can't do that due to performance reasons.
> 
> So for now we can workaround and offer proper rendering by disabling
> PSR2 and enabling in the worker a few miliseconds later if there is
> no other frontbuffer rendering.
> 
> This approach will eat some of the PSR2 power savings when userspace
> makes use of frontbuffer rendering but that is the solution that we
> can offer to enable PSR2 selective fetch right now while we work in
> the proper solution for frontbuffer rendering and PSR2.
> 
> Cc: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> ---
>   drivers/gpu/drm/i915/display/intel_psr.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> index a2e4ef42be60a..ba2da689920f9 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -1413,6 +1413,12 @@ static void psr_force_hw_tracking_exit(struct intel_dp *intel_dp)
>   {
>   	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
>   
> +	/* CURSURFLIVE has no effect when Selective fetch is enabled */
> +	if (intel_dp->psr.psr2_sel_fetch_enabled) {
> +		intel_psr_exit(intel_dp);
> +		return;
> +	}
> +
>   	/*
>   	 * Display WA #0884: skl+
>   	 * This documented WA for bxt can be safely applied
>