drm: Global atomic state handling

Some differences compared to Rob's patches again:
- Dropped the committed and checked booleans. Checking will be
  internally enforced by always calling ->atomic_check before
  ->atomic_commit. And async handling needs to be solved differently
  because the current scheme completely side-steps ww mutex deadlock
  avoidance (and so either reinvents a new deadlock avoidance wheel or
  like the current code just deadlocks).

- State for connectors needed to be added, since now they have a
  full-blown drm_connector_state (so that drivers have something to
  attach their own stuff to).

- Refcounting is gone. I plane to solve async updates differently,
  since the lock-passing scheme doesn't cut it (since it abuses ww
  mutexes). Essentially what we need for async is a simple ownership
  transfer from the caller to the driver. That doesn't need full-blown
  refcounting.

- The acquire ctx is a pointer. Real atomic callers should have that
  on their stack, legacy entry points need to put the right one
  (obtained by drm_modeset_legacy_acuire_ctx) in there.

- I've dropped all hooks except check/commit. All the begin/end
  handling is done by core functions and is the same.

- commit/check are just thin wrappers that ensure that ->check is
  always called.

- To help out with locking in the legacy implementations I've added a
  helper to just grab all locks in the backoff case.

v2: Add notices that check/commit can fail with EDEADLK.

v3:
- More consistent naming for state_alloc.
- Add state_clear which is needed for backoff and retry.

v4: Planes/connectors can switch between crtcs, and we need to be
careful that we grab the state (and locks) for both the old and new
crtc. Improve the interface functions to ensure this.

v5: Add functions to grab affected connectors for a crtc and to recompute
the crtc->enable state. This is useful for both helper and atomic ioctl
code when e.g. removing a connector.

v6: Squash in fixup from Fengguang to use ERR_CAST.

v7: Add debug output.

v8: Make checkpatch happy about kcalloc argument ordering.

v9: Improve kerneldoc in drm_crtc.h

v10:
- Fix another kcalloc argument misorder I've missed.
- More polish for kerneldoc.

v11: Clarify the ownership rules for the state object. The new rule is
that a successful drm_atomic_commit (whether synchronous or asnyc)
always inherits the state and is responsible for the clean-up. That
way async and sync ->commit functions are more similar.

v12: A few bugfixes:
- Assign state->state pointers correctly when grabbing state objects -
  we need to link them up with the global state.
- Handle a NULL crtc in set_crtc_for_plane to simplify code flow a bit
  for the callers of this function.

v13: Review from Sean:
- kerneldoc spelling fixes
- Don't overallocate states->planes.
- Handle NULL crtc in set_crtc_for_connector.

v14: Sprinkle __must_check over all functions which do wait/wound
locking to make sure callers don't forget this. Since I have ;-)

v15: Be more explicit in the kerneldoc when functions can return
-EDEADLK what to do. And that every other -errno is fatal.

v16: Indent with tabs instead of space, spotted by Ander.

v17: Review from Thierry, small kerneldoc and other naming polish.

Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 42 insertions, 8 deletions

diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 3554868dbf09..c7a3400173a8 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -227,7 +227,7 @@ struct drm_bridge;
 struct drm_atomic_state;
 
 /**
- * struct drm_crtc_state - mutable crtc state
+ * struct drm_crtc_state - mutable CRTC state
  * @enable: whether the CRTC should be enabled, gates all other state
  * @mode: current mode timings
  * @event: optional pointer to a DRM event to signal upon completion of the
@@ -235,7 +235,7 @@ struct drm_atomic_state;
  * @state: backpointer to global drm_atomic_state
  */
 struct drm_crtc_state {
-	bool enable        : 1;
+	bool enable;
 
 	struct drm_display_mode mode;
 
@@ -314,7 +314,7 @@ struct drm_crtc_funcs {
 	/* atomic update handling */
 	struct drm_crtc_state *(*atomic_duplicate_state)(struct drm_crtc *crtc);
 	void (*atomic_destroy_state)(struct drm_crtc *crtc,
-				     struct drm_crtc_state *cstate);
+				     struct drm_crtc_state *state);
 	int (*atomic_set_property)(struct drm_crtc *crtc,
 				   struct drm_crtc_state *state,
 				   struct drm_property *property,
@@ -417,7 +417,7 @@ struct drm_crtc {
 
 /**
  * struct drm_connector_state - mutable connector state
- * @crtc: crtc to connect connector to, NULL if disabled
+ * @crtc: CRTC to connect connector to, NULL if disabled
  * @state: backpointer to global drm_atomic_state
  */
 struct drm_connector_state {
@@ -441,7 +441,6 @@ struct drm_connector_state {
  * @atomic_destroy_state: destroy an atomic state for this connector
  * @atomic_set_property: set a property on an atomic state for this connector
  *
- *
  * Each CRTC may have one or more connectors attached to it.  The functions
  * below allow the core DRM code to control connectors, enumerate available modes,
  * etc.
@@ -469,7 +468,7 @@ struct drm_connector_funcs {
 	/* atomic update handling */
 	struct drm_connector_state *(*atomic_duplicate_state)(struct drm_connector *connector);
 	void (*atomic_destroy_state)(struct drm_connector *connector,
-				     struct drm_connector_state *cstate);
+				     struct drm_connector_state *state);
 	int (*atomic_set_property)(struct drm_connector *connector,
 				   struct drm_connector_state *state,
 				   struct drm_property *property,
@@ -640,7 +639,7 @@ struct drm_connector {
 /**
  * struct drm_plane_state - mutable plane state
  * @crtc: currently bound CRTC, NULL if disabled
- * @fb: currently bound fb
+ * @fb: currently bound framebuffer
  * @crtc_x: left position of visible portion of plane on crtc
  * @crtc_y: upper position of visible portion of plane on crtc
  * @crtc_w: width of visible portion of plane on crtc
@@ -697,7 +696,7 @@ struct drm_plane_funcs {
 	/* atomic update handling */
 	struct drm_plane_state *(*atomic_duplicate_state)(struct drm_plane *plane);
 	void (*atomic_destroy_state)(struct drm_plane *plane,
-				     struct drm_plane_state *cstate);
+				     struct drm_plane_state *state);
 	int (*atomic_set_property)(struct drm_plane *plane,
 				   struct drm_plane_state *state,
 				   struct drm_property *property,
@@ -794,6 +793,32 @@ struct drm_bridge {
 };
 
 /**
+ * struct struct drm_atomic_state - the global state object for atomic updates
+ * @dev: parent DRM device
+ * @flags: state flags like async update
+ * @planes: pointer to array of plane pointers
+ * @plane_states: pointer to array of plane states pointers
+ * @crtcs: pointer to array of CRTC pointers
+ * @crtc_states: pointer to array of CRTC states pointers
+ * @connectors: pointer to array of connector pointers
+ * @connector_states: pointer to array of connector states pointers
+ * @acquire_ctx: acquire context for this atomic modeset state update
+ */
+struct drm_atomic_state {
+	struct drm_device *dev;
+	uint32_t flags;
+	struct drm_plane **planes;
+	struct drm_plane_state **plane_states;
+	struct drm_crtc **crtcs;
+	struct drm_crtc_state **crtc_states;
+	struct drm_connector **connectors;
+	struct drm_connector_state **connector_states;
+
+	struct drm_modeset_acquire_ctx *acquire_ctx;
+};
+
+
+/**
  * struct drm_mode_set - new values for a CRTC config change
  * @fb: framebuffer to use for new config
  * @crtc: CRTC whose configuration we're about to change
@@ -824,6 +849,9 @@ struct drm_mode_set {
  * struct drm_mode_config_funcs - basic driver provided mode setting functions
  * @fb_create: create a new framebuffer object
  * @output_poll_changed: function to handle output configuration changes
+ * @atomic_check: check whether a give atomic state update is possible
+ * @atomic_commit: commit an atomic state update previously verified with
+ * 	atomic_check()
  *
  * Some global (i.e. not per-CRTC, connector, etc) mode setting functions that
  * involve drivers.
@@ -833,6 +861,12 @@ struct drm_mode_config_funcs {
 					     struct drm_file *file_priv,
 					     struct drm_mode_fb_cmd2 *mode_cmd);
 	void (*output_poll_changed)(struct drm_device *dev);
+
+	int (*atomic_check)(struct drm_device *dev,
+			    struct drm_atomic_state *a);
+	int (*atomic_commit)(struct drm_device *dev,
+			     struct drm_atomic_state *a,
+			     bool async);
 };
 
 /**