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Commit c9855a56 authored by Maarten Lankhorst's avatar Maarten Lankhorst
Browse files

drm/i915: Block enabling FBC until flips have been completed 



There is a small race window in which FBC can be enabled after
pre_plane_update is called, but before the page flip has been
queued or completed.

Signed-off-by: default avatarMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103167
Link: https://patchwork.freedesktop.org/patch/msgid/20180625163758.10871-1-maarten.lankhorst@linux.intel.com


Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
parent 9512f985

drivers/gpu/drm/i915/i915_drv.h

+1 −0
Original line number Diff line number Diff line
@@ -512,6 +512,7 @@ struct intel_fbc { 


	bool enabled;

	bool active;

	bool flip_pending;



	bool underrun_detected;

	struct work_struct underrun_work;

drivers/gpu/drm/i915/intel_fbc.c

+11 −24
Original line number Diff line number Diff line
@@ -924,13 +924,6 @@ static void intel_fbc_get_reg_params(struct intel_crtc *crtc, 
						32 * fbc->threshold) * 8;

}



static bool intel_fbc_reg_params_equal(struct intel_fbc_reg_params *params1,

				       struct intel_fbc_reg_params *params2)

{

	/* We can use this since intel_fbc_get_reg_params() does a memset. */

	return memcmp(params1, params2, sizeof(*params1)) == 0;

}



void intel_fbc_pre_update(struct intel_crtc *crtc,

			  struct intel_crtc_state *crtc_state,

			  struct intel_plane_state *plane_state)
@@ -953,6 +946,7 @@ void intel_fbc_pre_update(struct intel_crtc *crtc, 
		goto unlock;



	intel_fbc_update_state_cache(crtc, crtc_state, plane_state);

	fbc->flip_pending = true;



deactivate:

	intel_fbc_deactivate(dev_priv, reason);
@@ -988,13 +982,15 @@ static void __intel_fbc_post_update(struct intel_crtc *crtc) 
{

	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);

	struct intel_fbc *fbc = &dev_priv->fbc;

	struct intel_fbc_reg_params old_params;



	WARN_ON(!mutex_is_locked(&fbc->lock));



	if (!fbc->enabled || fbc->crtc != crtc)

		return;



	fbc->flip_pending = false;

	WARN_ON(fbc->active);



	if (!i915_modparams.enable_fbc) {

		intel_fbc_deactivate(dev_priv, "disabled at runtime per module param");

		__intel_fbc_disable(dev_priv);
@@ -1002,25 +998,16 @@ static void __intel_fbc_post_update(struct intel_crtc *crtc) 
		return;

	}



	if (!intel_fbc_can_activate(crtc)) {

		WARN_ON(fbc->active);

		return;

	}



	old_params = fbc->params;

	intel_fbc_get_reg_params(crtc, &fbc->params);



	/* If the scanout has not changed, don't modify the FBC settings.

	 * Note that we make the fundamental assumption that the fb->obj

	 * cannot be unpinned (and have its GTT offset and fence revoked)

	 * without first being decoupled from the scanout and FBC disabled.

	 */

	if (fbc->active &&

	    intel_fbc_reg_params_equal(&old_params, &fbc->params))

	if (!intel_fbc_can_activate(crtc))

		return;



	if (!fbc->busy_bits) {

		intel_fbc_deactivate(dev_priv, "FBC enabled (active or scheduled)");

		intel_fbc_schedule_activation(crtc);

	} else

		intel_fbc_deactivate(dev_priv, "frontbuffer write");

}



void intel_fbc_post_update(struct intel_crtc *crtc)
@@ -1085,7 +1072,7 @@ void intel_fbc_flush(struct drm_i915_private *dev_priv, 
	    (frontbuffer_bits & intel_fbc_get_frontbuffer_bit(fbc))) {

		if (fbc->active)

			intel_fbc_recompress(dev_priv);

		else

		else if (!fbc->flip_pending)

			__intel_fbc_post_update(fbc->crtc);

	}