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

On Wed, Aug 12, 2015 at 04:37:28PM +0200, Thierry Reding wrote:

From: Thierry Reding treding@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@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.

s/guaranteed/is possible and won't result in confusion/ maybe?

• • Calls to this function must be guarded by drm_modeset_lock_all() and
• • drm_modeset_unlock_all().

If you pass in the acquire ctx explicitly this isn't strictly true since you're using the get_*_state functions, which might return -EDEADLK. So maybe instead:

"Note that if callers haven't already acquired all modeset locks this might return -EDEADLK, which must be handled by the caller using rm_modeset_backoff()."

• • 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;

The hidden acquire_ctx was just a hack to avoid needing to redo _all_ driver entry points by adding a ctx parameter. I want to remove this long-term, so please don't spread it and instead just add a ctx parameter to this function.

Didn't spot anything else. -Daniel

• 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