[PATCH] drm/atomic-helper: add unlocked disable all outputs helper

[Lucas Stach]

This adds the unlocked variant of drm_atomic_helper_disable_all(),
which takes all the required modeset locks itself. This is intended
to be used when shutting down the driver, without retaining any
state.

Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
---
 drivers/gpu/drm/drm_atomic_helper.c | 43 +++++++++++++++++++++++++++++++++++++
 include/drm/drm_atomic_helper.h     |  1 +
 2 files changed, 44 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 99365087645b..6673021ab21e 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2435,6 +2435,49 @@ free:
 EXPORT_SYMBOL(drm_atomic_helper_disable_all);
 
 /**
+ * drm_atomic_helper_disable_all_unlocked - disable all currently active
+ * outputs taking the modeset locks itself
+ * @dev: DRM device
+ *
+ * Loops through all connectors, finding those that aren't turned off and then
+ * turns them off by setting their DPMS mode to OFF and deactivating the CRTC
+ * that they are connected to.
+ *
+ * This is used for example when shutting down the DRM device.
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_atomic_helper_disable_all_unlocked(struct drm_device *dev)
+{
+	struct drm_modeset_acquire_ctx ctx;
+	int err;
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+retry:
+	err = drm_modeset_lock_all_ctx(dev, &ctx);
+	if (err < 0)
+		goto unlock;
+
+	err = drm_atomic_helper_disable_all(dev, &ctx);
+	if (err < 0)
+		goto unlock;
+
+unlock:
+	if (err == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry;
+	}
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+
+	return err;
+}
+EXPORT_SYMBOL(drm_atomic_helper_disable_all_unlocked);
+
+/**
  * drm_atomic_helper_suspend - subsystem-level suspend helper
  * @dev: DRM device
  *
diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h
index d86ae5dcd7b4..104d310c2c70 100644
--- a/include/drm/drm_atomic_helper.h
+++ b/include/drm/drm_atomic_helper.h
@@ -99,6 +99,7 @@ int __drm_atomic_helper_set_config(struct drm_mode_set *set,
 
 int drm_atomic_helper_disable_all(struct drm_device *dev,
 				  struct drm_modeset_acquire_ctx *ctx);
+int drm_atomic_helper_disable_all_unlocked(struct drm_device *dev);
 struct drm_atomic_state *drm_atomic_helper_suspend(struct drm_device *dev);
 int drm_atomic_helper_resume(struct drm_device *dev,
 			     struct drm_atomic_state *state);
-- 
2.8.1