Re: [Intel-gfx] [PATCH 1/4] drm/i915/display/tgl+: Dispatch atomic commits instead of front buffer modifications

["Souza, Jose" <jose.souza@intel.com>]

On Fri, 2021-07-30 at 17:10 -0700, José Roberto de Souza wrote:
> PSR2 selective fetch requires plane and transcoder registers to
> be programed during the vblank to properly update the display and
> there is no way around it.
> 
> We could disable PSR2 at every notification of dirty front buffer from
> user space but that would hurt the power savings and it would still
> cause some race conditions between PSR2 exit sequence and atomic
> commits that causes underruns and glitches.
> 
> So from display 12 and newer we will start to do atomic commits
> every time user space notify that front buffer is dirty and ignore
> all frontbuffer flushes and invalidates on the PSR side.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>

> 
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Gwan-gyeong Mun <gwan-gyeong.mun@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_cursor.c  | 3 ++-
>  drivers/gpu/drm/i915/display/intel_display.c | 7 ++++++-
>  drivers/gpu/drm/i915/display/intel_psr.c     | 6 ++++++
>  3 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c
> index c7618fef01439..d44022cb46a65 100644
> --- a/drivers/gpu/drm/i915/display/intel_cursor.c
> +++ b/drivers/gpu/drm/i915/display/intel_cursor.c
> @@ -617,6 +617,7 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
>  			   u32 src_w, u32 src_h,
>  			   struct drm_modeset_acquire_ctx *ctx)
>  {
> +	struct drm_i915_private *i915 = to_i915(_crtc->dev);
>  	struct intel_plane *plane = to_intel_plane(_plane);
>  	struct intel_crtc *crtc = to_intel_crtc(_crtc);
>  	struct intel_plane_state *old_plane_state =
> @@ -638,7 +639,7 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
>  	 */
>  	if (!crtc_state->hw.active || intel_crtc_needs_modeset(crtc_state) ||
>  	    crtc_state->update_pipe || crtc_state->bigjoiner ||
> -	    crtc_state->enable_psr2_sel_fetch)
> +	    DISPLAY_VER(i915) >= 12)
>  		goto slow;
>  
>  	/*
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 5ff0a011b28eb..4a936e1e7fa82 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -11720,10 +11720,15 @@ static int intel_user_framebuffer_dirty(struct drm_framebuffer *fb,
>  					unsigned num_clips)
>  {
>  	struct drm_i915_gem_object *obj = intel_fb_obj(fb);
> +	struct drm_i915_private *i915 = to_i915(obj->base.dev);
>  
>  	i915_gem_object_flush_if_display(obj);
> -	intel_frontbuffer_flush(to_intel_frontbuffer(fb), ORIGIN_DIRTYFB);
>  
> +	if (DISPLAY_VER(i915) >= 12)
> +		return drm_atomic_helper_dirtyfb(fb, file, flags, color, clips,
> +						 num_clips);
> +
> +	intel_frontbuffer_flush(to_intel_frontbuffer(fb), ORIGIN_DIRTYFB);
>  	return 0;
>  }
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> index 1b0daf649e823..caf92f414a6e7 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -2039,6 +2039,9 @@ void intel_psr_invalidate(struct drm_i915_private *dev_priv,
>  {
>  	struct intel_encoder *encoder;
>  
> +	if (DISPLAY_VER(dev_priv) >= 12)
> +		return;
> +
>  	if (origin == ORIGIN_FLIP)
>  		return;
>  
> @@ -2123,6 +2126,9 @@ void intel_psr_flush(struct drm_i915_private *dev_priv,
>  			continue;
>  		}
>  
> +		if (DISPLAY_VER(dev_priv) >= 12)
> +			continue;
> +
>  		mutex_lock(&intel_dp->psr.lock);
>  		if (!intel_dp->psr.enabled) {
>  			mutex_unlock(&intel_dp->psr.lock);