[PATCH v2 8/9] drm/atomic-helper: Re-order bridge chain pre-enable and post-disable

[Aradhya Bhatia]

Move the bridge pre_enable call before crtc enable, and the bridge
post_disable call after the crtc disable.

The sequence of enable after this patch will look like:

	bridge[n]_pre_enable
	...
	bridge[1]_pre_enable

	crtc_enable
	encoder_enable

	bridge[1]_enable
	...
	bridge[n]__enable

and vice-versa for the bridge chain disable sequence.

The definition of bridge pre_enable hook says that,
"The display pipe (i.e. clocks and timing signals) feeding this bridge
will not yet be running when this callback is called".

Since CRTC is also a source feeding the bridge, it should not be enabled
before the bridges in the pipeline are pre_enabled. Fix that by
re-ordering the sequence of bridge pre_enable and bridge post_disable.

Signed-off-by: Aradhya Bhatia <a-bhatia1@xxxxxx>
---
 drivers/gpu/drm/drm_atomic_helper.c | 70 +++++++++++++++++++++++++++--
 1 file changed, 67 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index fb97b51b38f1..02e093950218 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1186,8 +1186,6 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
 			else if (funcs->dpms)
 				funcs->dpms(encoder, DRM_MODE_DPMS_OFF);
 		}
-
-		drm_atomic_bridge_chain_post_disable(bridge, old_state);
 	}
 
 	for_each_oldnew_crtc_in_state(old_state, crtc, old_crtc_state, new_crtc_state, i) {
@@ -1234,6 +1232,49 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
 		if (ret == 0)
 			drm_crtc_vblank_put(crtc);
 	}
+
+	for_each_oldnew_connector_in_state(old_state, connector, old_conn_state,
+					   new_conn_state, i) {
+		struct drm_encoder *encoder;
+		struct drm_bridge *bridge;
+
+		/*
+		 * Shut down everything that's in the changeset and currently
+		 * still on. So need to check the old, saved state.
+		 */
+		if (!old_conn_state->crtc)
+			continue;
+
+		old_crtc_state = drm_atomic_get_old_crtc_state(old_state, old_conn_state->crtc);
+
+		if (new_conn_state->crtc)
+			new_crtc_state = drm_atomic_get_new_crtc_state(old_state,
+								       new_conn_state->crtc);
+		else
+			new_crtc_state = NULL;
+
+		if (!crtc_needs_disable(old_crtc_state, new_crtc_state) ||
+		    !drm_atomic_crtc_needs_modeset(old_conn_state->crtc->state))
+			continue;
+
+		encoder = old_conn_state->best_encoder;
+
+		/* We shouldn't get this far if we didn't previously have
+		 * an encoder.. but WARN_ON() rather than explode.
+		 */
+		if (WARN_ON(!encoder))
+			continue;
+
+		drm_dbg_atomic(dev, "disabling [ENCODER:%d:%s]\n",
+			       encoder->base.id, encoder->name);
+
+		/*
+		 * Each encoder has at most one connector (since we always steal
+		 * it away), so we won't call disable hooks twice.
+		 */
+		bridge = drm_bridge_chain_get_first_bridge(encoder);
+		drm_atomic_bridge_chain_post_disable(bridge, old_state);
+	}
 }
 
 /**
@@ -1469,6 +1510,30 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
 	struct drm_connector_state *new_conn_state;
 	int i;
 
+	for_each_new_connector_in_state(old_state, connector, new_conn_state, i) {
+		struct drm_encoder *encoder;
+		struct drm_bridge *bridge;
+
+		if (!new_conn_state->best_encoder)
+			continue;
+
+		if (!new_conn_state->crtc->state->active ||
+		    !drm_atomic_crtc_needs_modeset(new_conn_state->crtc->state))
+			continue;
+
+		encoder = new_conn_state->best_encoder;
+
+		drm_dbg_atomic(dev, "enabling [ENCODER:%d:%s]\n",
+			       encoder->base.id, encoder->name);
+
+		/*
+		 * Each encoder has at most one connector (since we always steal
+		 * it away), so we won't call enable hooks twice.
+		 */
+		bridge = drm_bridge_chain_get_first_bridge(encoder);
+		drm_atomic_bridge_chain_pre_enable(bridge, old_state);
+	}
+
 	for_each_oldnew_crtc_in_state(old_state, crtc, old_crtc_state, new_crtc_state, i) {
 		const struct drm_crtc_helper_funcs *funcs;
 
@@ -1514,7 +1579,6 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
 		 * it away), so we won't call enable hooks twice.
 		 */
 		bridge = drm_bridge_chain_get_first_bridge(encoder);
-		drm_atomic_bridge_chain_pre_enable(bridge, old_state);
 
 		if (funcs) {
 			if (funcs->atomic_enable)
-- 
2.34.1