[PATCH v2 1/3] drm/atomic-helper: Implement drm_atomic_helper_duplicate_state()

[Thierry Reding]

From: Thierry Reding <treding at nvidia.com>

This function can be used to duplicate an atomic state object. This is
useful for example to implement suspend/resume, where the state before
suspend can be saved and restored upon resume.

v2: move locking to caller, be more explicit about prerequisites

Signed-off-by: Thierry Reding <treding at nvidia.com>
---
 drivers/gpu/drm/drm_atomic_helper.c | 80 +++++++++++++++++++++++++++++++++++++
 include/drm/drm_atomic_helper.h     |  2 +
 2 files changed, 82 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index fd06595c2ee5..1f84df3b0a5d 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2358,6 +2358,86 @@ drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector)
 EXPORT_SYMBOL(drm_atomic_helper_connector_duplicate_state);
 
 /**
+ * drm_atomic_helper_duplicate_state - duplicate an atomic state object
+ * @dev: DRM device
+ *
+ * Makes a copy of the current atomic state by looping over all objects and
+ * duplicating their respective states. This is used for example by suspend/
+ * resume support code to save the state prior to suspend such that it can
+ * be restored upon resume.
+ *
+ * Note that this treats atomic state as persistent between save and restore.
+ * Drivers must make sure that this is guaranteed.
+ *
+ * Calls to this function must be guarded by drm_modeset_lock_all() and
+ * drm_modeset_unlock_all().
+ *
+ * Returns:
+ * A pointer to the copy of the atomic state object on success or an
+ * ERR_PTR()-encoded error code on failure.
+ */
+struct drm_atomic_state *
+drm_atomic_helper_duplicate_state(struct drm_device *dev)
+{
+	struct drm_atomic_state *state;
+	struct drm_connector *conn;
+	struct drm_plane *plane;
+	struct drm_crtc *crtc;
+	int err = 0;
+
+	if (WARN_ON(!dev->mode_config.acquire_ctx))
+		return ERR_PTR(-EINVAL);
+
+	state = drm_atomic_state_alloc(dev);
+	if (!state)
+		return ERR_PTR(-ENOMEM);
+
+	state->acquire_ctx = dev->mode_config.acquire_ctx;
+
+	drm_for_each_crtc(crtc, dev) {
+		struct drm_crtc_state *crtc_state;
+
+		crtc_state = drm_atomic_get_crtc_state(state, crtc);
+		if (IS_ERR(crtc_state)) {
+			err = PTR_ERR(crtc_state);
+			goto free;
+		}
+	}
+
+	drm_for_each_plane(plane, dev) {
+		struct drm_plane_state *plane_state;
+
+		plane_state = drm_atomic_get_plane_state(state, plane);
+		if (IS_ERR(plane_state)) {
+			err = PTR_ERR(plane_state);
+			goto free;
+		}
+	}
+
+	drm_for_each_connector(conn, dev) {
+		struct drm_connector_state *conn_state;
+
+		conn_state = drm_atomic_get_connector_state(state, conn);
+		if (IS_ERR(conn_state)) {
+			err = PTR_ERR(conn_state);
+			goto free;
+		}
+	}
+
+	/* clear the acquire context so that it isn't accidentally reused */
+	state->acquire_ctx = NULL;
+
+free:
+	if (err < 0) {
+		drm_atomic_state_free(state);
+		state = ERR_PTR(err);
+	}
+
+	return state;
+}
+EXPORT_SYMBOL(drm_atomic_helper_duplicate_state);
+
+/**
  * __drm_atomic_helper_connector_destroy_state - release connector state
  * @connector: connector object
  * @state: connector state object to release
diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h
index 4ffe9dca07c4..5d27612997ce 100644
--- a/include/drm/drm_atomic_helper.h
+++ b/include/drm/drm_atomic_helper.h
@@ -118,6 +118,8 @@ __drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector,
 					   struct drm_connector_state *state);
 struct drm_connector_state *
 drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector);
+struct drm_atomic_state *
+drm_atomic_helper_duplicate_state(struct drm_device *dev);
 void
 __drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
 					    struct drm_connector_state *state);
-- 
2.4.5