Re: [PATCH] drm/i915: Postpone plane readout until after encoder readout, v3.

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

On Thu, Aug 27, 2015 at 01:47:26PM +0200, Maarten Lankhorst wrote:
> When reading out hw state for planes we disable inactive planes which in
> turn triggers an update of the watermarks. The update depends on the
> crtc_clock being set which is done when reading out encoders. Thus
> postpone the plane readout until after encoder readout.
> 
> This prevents a warning in skl_compute_linetime_wm() where pixel_rate
> becomes 0 when crtc_clock is 0.
> 
> Signed-off-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> References: https://bugs.freedesktop.org/show_bug.cgi?id=91428
> ---
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index e3922d973db0..118b205e7bd5 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -15033,30 +15033,6 @@ static bool primary_get_hw_state(struct intel_crtc *crtc)
>  	return !!(I915_READ(DSPCNTR(crtc->plane)) & DISPLAY_PLANE_ENABLE);
>  }
>  
> -static void readout_plane_state(struct intel_crtc *crtc,
> -				struct intel_crtc_state *crtc_state)
> -{
> -	struct intel_plane *p;
> -	struct intel_plane_state *plane_state;
> -	bool active = crtc_state->base.active;
> -
> -	for_each_intel_plane(crtc->base.dev, p) {
> -		if (crtc->pipe != p->pipe)
> -			continue;
> -
> -		plane_state = to_intel_plane_state(p->base.state);
> -
> -		if (p->base.type == DRM_PLANE_TYPE_PRIMARY)
> -			plane_state->visible = primary_get_hw_state(crtc);
> -		else {
> -			if (active)
> -				p->disable_plane(&p->base, &crtc->base);
> -
> -			plane_state->visible = false;
> -		}
> -	}
> -}
> -
>  static void intel_modeset_readout_hw_state(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> @@ -15076,35 +15052,8 @@ static void intel_modeset_readout_hw_state(struct drm_device *dev)
>  
>  		crtc->base.state->active = crtc->active;
>  		crtc->base.enabled = crtc->active;
> -
> -		memset(&crtc->base.mode, 0, sizeof(crtc->base.mode));
> -		if (crtc->base.state->active) {
> -			intel_mode_from_pipe_config(&crtc->base.mode, crtc->config);
> -			intel_mode_from_pipe_config(&crtc->base.state->adjusted_mode, crtc->config);
> -			WARN_ON(drm_atomic_set_mode_for_crtc(crtc->base.state, &crtc->base.mode));
> -
> -			/*
> -			 * The initial mode needs to be set in order to keep
> -			 * the atomic core happy. It wants a valid mode if the
> -			 * crtc's enabled, so we do the above call.
> -			 *
> -			 * At this point some state updated by the connectors
> -			 * in their ->detect() callback has not run yet, so
> -			 * no recalculation can be done yet.
> -			 *
> -			 * Even if we could do a recalculation and modeset
> -			 * right now it would cause a double modeset if
> -			 * fbdev or userspace chooses a different initial mode.
> -			 *
> -			 * If that happens, someone indicated they wanted a
> -			 * mode change, which means it's safe to do a full
> -			 * recalculation.
> -			 */
> -			crtc->base.state->mode.private_flags = I915_MODE_FLAG_INHERITED;
> -		}
> -
> -		crtc->base.hwmode = crtc->config->base.adjusted_mode;
> -		readout_plane_state(crtc, to_intel_crtc_state(crtc->base.state));
> +		to_intel_plane_state(crtc->base.primary->state)->visible =
> +			primary_get_hw_state(crtc);

The commit message is for a totally different patch it seems.

Hmm. Looking at this, I should have just moved the entire mode setup
block in my hwmode fix patch to the end of the function, and things would
be fixed.

>  
>  		DRM_DEBUG_KMS("[CRTC:%d] hw state readout: %s\n",
>  			      crtc->base.base.id,
> @@ -15186,6 +15135,33 @@ intel_modeset_setup_hw_state(struct drm_device *dev)
>  
>  	for_each_pipe(dev_priv, pipe) {
>  		crtc = to_intel_crtc(dev_priv->pipe_to_crtc_mapping[pipe]);
> +		crtc->base.hwmode = crtc->config->base.adjusted_mode;
> +		memset(&crtc->base.mode, 0, sizeof(crtc->base.mode));
> +		if (crtc->base.state->active) {
> +			intel_mode_from_pipe_config(&crtc->base.mode, crtc->config);
> +			intel_mode_from_pipe_config(&crtc->base.state->adjusted_mode, crtc->config);
> +			WARN_ON(drm_atomic_set_mode_for_crtc(crtc->base.state, &crtc->base.mode));
> +
> +			/*
> +			 * The initial mode needs to be set in order to keep
> +			 * the atomic core happy. It wants a valid mode if the
> +			 * crtc's enabled, so we do the above call.
> +			 *
> +			 * At this point some state updated by the connectors
> +			 * in their ->detect() callback has not run yet, so
> +			 * no recalculation can be done yet.
> +			 *
> +			 * Even if we could do a recalculation and modeset
> +			 * right now it would cause a double modeset if
> +			 * fbdev or userspace chooses a different initial mode.
> +			 *
> +			 * If that happens, someone indicated they wanted a
> +			 * mode change, which means it's safe to do a full
> +			 * recalculation.
> +			 */
> +			crtc->base.state->mode.private_flags = I915_MODE_FLAG_INHERITED;
> +		}
> +

Why not keep it in intel_modeset_readout_hw_state()? That way all the
low level gunk stays in intel_modeset_readout_hw_state() and
intel_modeset_setup_hw_state() just has the higher level stuff.

>  		intel_sanitize_crtc(crtc);
>  		intel_dump_pipe_config(crtc, crtc->config,
>  				       "[setup_hw_state]");
> 
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-- 
Ville Syrjälä
Intel OTC
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