[PATCH v8 11/13] drm/atomic-helper: Separate out bridge pre_enable/post_disable from enable/disable

Aradhya Bhatia
2025-01-26T19:17:37Z

The encoder-bridge ops occur by looping over the new connector states of
the display pipelines. The enable sequence runs as follows -

- pre_enable(bridge),
- enable(encoder),
- enable(bridge),

while the disable sequnce runs as follows -

- disable(bridge),
- disable(encoder),
- post_disable(bridge).

Separate out the pre_enable(bridge), and the post_disable(bridge)
operations into separate functions each.

This patch keeps the sequence same for any singular disaplay pipe, but
changes the sequence across multiple display pipelines.

This patch is meant to be an interim patch, to cleanly pave the way for
the sequence re-ordering patch, and maintain bisectability in the
process.

Signed-off-by: Aradhya Bhatia <aradhya.bhatia@linux.dev>
---
drivers/gpu/drm/drm_atomic_helper.c | 92 +++++++++++++++++++++++++++--
1 file changed, 88 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index e805fd0a54c5..f5532e3646e1 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1185,8 +1185,6 @@ encoder_bridge_disable(struct drm_device *dev, struct drm_atomic_state *old_stat
else if (funcs->dpms)
funcs->dpms(encoder, DRM_MODE_DPMS_OFF);
}
-
- drm_atomic_bridge_chain_post_disable(bridge, old_state);
}
}

@@ -1243,11 +1241,65 @@ crtc_disable(struct drm_device *dev, struct drm_atomic_state *old_state)
}
}

+static void
+encoder_bridge_post_disable(struct drm_device *dev, struct drm_atomic_state *old_state)
+{
+ struct drm_connector *connector;
+ struct drm_connector_state *old_conn_state, *new_conn_state;
+ struct drm_crtc_state *old_crtc_state, *new_crtc_state;
+ int i;
+
+ 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, "post-disabling bridges [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);
+ }
+}
+
static void
disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
{
encoder_bridge_disable(dev, old_state);

+ encoder_bridge_post_disable(dev, old_state);
+
crtc_disable(dev, old_state);
}

@@ -1460,6 +1512,38 @@ static void drm_atomic_helper_commit_writebacks(struct drm_device *dev,
}
}

+static void
+encoder_bridge_pre_enable(struct drm_device *dev, struct drm_atomic_state *old_state)
+{
+ struct drm_connector *connector;
+ 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, "pre-enabling bridges [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);
+ }
+}
+
static void
crtc_enable(struct drm_device *dev, struct drm_atomic_state *old_state)
{
@@ -1531,8 +1615,6 @@ encoder_bridge_enable(struct drm_device *dev, struct drm_atomic_state *old_state
else if (funcs->commit)
funcs->commit(encoder);
}
-
- drm_atomic_bridge_chain_enable(bridge, old_state);
}
}

@@ -1555,6 +1637,8 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
{
crtc_enable(dev, old_state);

+ encoder_bridge_pre_enable(dev, old_state);
+
encoder_bridge_enable(dev, old_state);

drm_atomic_helper_commit_writebacks(dev, old_state);
--
2.34.1