[PATCH v6 4/5] drm: Connector helper function to release resources

[Dhinakaran Pandiyan]

From: "Pandiyan, Dhinakaran" <dhinakaran.pandiyan at intel.com>

Having an ->atomic_release callback is useful to release shared resources
that get allocated in compute_config(). This function is expected to be
called in the atomic_check() phase before new resources are acquired.

v5: Return an int (Maarten)
v4: Document that the function is conditionally called and before
other atomic_checks() (Daniel)
v3: Use the new 'for_each_oldnew_connector_in_state()' macro.
v2: Moved the caller hunk to this patch (Daniel)

Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Archit Taneja <architt at codeaurora.org>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Harry Wentland <Harry.wentland at amd.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
Suggested-by: Daniel Vetter <daniel.vetter at ffwll.ch>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
---
 drivers/gpu/drm/drm_atomic_helper.c      | 22 ++++++++++++++++++++++
 include/drm/drm_modeset_helper_vtables.h | 20 ++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index d14094d..57d2e50 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -586,6 +586,28 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
 		}
 	}
 
+	for_each_oldnew_connector_in_state(state, connector, old_connector_state, new_connector_state, i) {
+		const struct drm_connector_helper_funcs *conn_funcs;
+		struct drm_crtc_state *crtc_state;
+
+		conn_funcs = connector->helper_private;
+		if (!conn_funcs->atomic_release)
+			continue;
+
+		if (!old_connector_state->crtc)
+			continue;
+
+		crtc_state = drm_atomic_get_existing_crtc_state(state, old_connector_state->crtc);
+
+		if (crtc_state->connectors_changed ||
+		    crtc_state->mode_changed ||
+		    (crtc_state->active_changed && !crtc_state->active)) {
+			ret = conn_funcs->atomic_release(connector, new_connector_state);
+			if (ret != 0)
+				return ret;
+		}
+	}
+
 	return mode_fixup(state);
 }
 EXPORT_SYMBOL(drm_atomic_helper_check_modeset);
diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index 091c422..36a4b16 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -836,6 +836,26 @@ struct drm_connector_helper_funcs {
 	 */
 	struct drm_encoder *(*atomic_best_encoder)(struct drm_connector *connector,
 						   struct drm_connector_state *connector_state);
+
+	/**
+	 * @atomic_release:
+	 *
+	 * This function is conditionally called to release shared resources
+	 * when the attached CRTC's mode changes or it's connectors change or
+	 * becomes inactive. It is called before the corresponding
+	 * &drm_crtc_helper_funcs.atomic_check or
+	 * &drm_crtc_helper_funcs.mode_fixup hooks are called.
+	 *
+	 * NOTE:
+	 *
+	 * This function is called in the check phase of an atomic update.
+	 *
+	 * RETURNS:
+	 *
+	 * 0 on success or negative error codes on failure.
+	 */
+	int (*atomic_release)(struct drm_connector *connector,
+			       struct drm_connector_state *connector_state);
 };
 
 /**
-- 
2.7.4