drm: Add driver-private objects to atomic state

It is necessary to track states for objects other than connector, crtc
and plane for atomic modesets. But adding objects like DP MST link
bandwidth to drm_atomic_state would mean that a non-core object will be
modified by the core helper functions for swapping and clearing
it's state. So, lets add void * objects and helper functions that operate
on void * types to keep these objects and states private to the core.
Drivers can then implement specific functions to swap and clear states.
The other advantage having just void * for these objects in
drm_atomic_state is that objects of different types can be managed in the
same state array.

v7: Use __for_each_private_obj to define for_each_private_obj (Maarten)
v6: More kernel-doc to keep 0-day happy
v5: Remove more NULL checks (Maarten)
v4: Avoid redundant NULL checks when private_objs array is empty (Maarten)
v3: Macro alignment (Chris)
v2: Added docs and new iterator to filter private objects (Daniel)

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Archit Taneja <architt@codeaurora.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Harry Wentland <Harry.wentland@amd.com>

Acked-by: Harry Wentland <harry.wentland@amd.com>
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1492753893-3748-2-git-send-email-dhinakaran.pandiyan@intel.com

drivers/gpu/drm/drm_atomic.c

@@ -57,6 +57,7 @@ void drm_atomic_state_default_release(struct drm_atomic_state *state)
 	kfree(state->connectors);
 	kfree(state->crtcs);
 	kfree(state->planes);
+	kfree(state->private_objs);
 }
 EXPORT_SYMBOL(drm_atomic_state_default_release);
 
@@ -184,6 +185,17 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
 		state->planes[i].ptr = NULL;
 		state->planes[i].state = NULL;
 	}
+
+	for (i = 0; i < state->num_private_objs; i++) {
+		void *obj_state = state->private_objs[i].obj_state;
+
+		state->private_objs[i].funcs->destroy_state(obj_state);
+		state->private_objs[i].obj = NULL;
+		state->private_objs[i].obj_state = NULL;
+		state->private_objs[i].funcs = NULL;
+	}
+	state->num_private_objs = 0;
+
 }
 EXPORT_SYMBOL(drm_atomic_state_default_clear);
 
@@ -977,6 +989,59 @@ static void drm_atomic_plane_print_state(struct drm_printer *p,
 		plane->funcs->atomic_print_state(p, state);
 }
 
+/**
+ * drm_atomic_get_private_obj_state - get private object state
+ * @state: global atomic state
+ * @obj: private object to get the state for
+ * @funcs: pointer to the struct of function pointers that identify the object
+ * type
+ *
+ * This function returns the private object state for the given private object,
+ * allocating the state if needed. It does not grab any locks as the caller is
+ * expected to care of any required locking.
+ *
+ * RETURNS:
+ *
+ * Either the allocated state or the error code encoded into a pointer.
+ */
+void *
+drm_atomic_get_private_obj_state(struct drm_atomic_state *state, void *obj,
+			      const struct drm_private_state_funcs *funcs)
+{
+	int index, num_objs, i;
+	size_t size;
+	struct __drm_private_objs_state *arr;
+
+	for (i = 0; i < state->num_private_objs; i++)
+		if (obj == state->private_objs[i].obj &&
+		    state->private_objs[i].obj_state)
+			return state->private_objs[i].obj_state;
+
+	num_objs = state->num_private_objs + 1;
+	size = sizeof(*state->private_objs) * num_objs;
+	arr = krealloc(state->private_objs, size, GFP_KERNEL);
+	if (!arr)
+		return ERR_PTR(-ENOMEM);
+
+	state->private_objs = arr;
+	index = state->num_private_objs;
+	memset(&state->private_objs[index], 0, sizeof(*state->private_objs));
+
+	state->private_objs[index].obj_state = funcs->duplicate_state(state, obj);
+	if (!state->private_objs[index].obj_state)
+		return ERR_PTR(-ENOMEM);
+
+	state->private_objs[index].obj = obj;
+	state->private_objs[index].funcs = funcs;
+	state->num_private_objs = num_objs;
+
+	DRM_DEBUG_ATOMIC("Added new private object state %p to %p\n",
+			 state->private_objs[index].obj_state, state);
+
+	return state->private_objs[index].obj_state;
+}
+EXPORT_SYMBOL(drm_atomic_get_private_obj_state);
+
 /**
  * drm_atomic_get_connector_state - get connector state
  * @state: global atomic state object

drivers/gpu/drm/drm_atomic_helper.c

@@ -2032,6 +2032,8 @@ void drm_atomic_helper_swap_state(struct drm_atomic_state *state,
 	struct drm_plane *plane;
 	struct drm_plane_state *old_plane_state, *new_plane_state;
 	struct drm_crtc_commit *commit;
+	void *obj, *obj_state;
+	const struct drm_private_state_funcs *funcs;
 
 	if (stall) {
 		for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
@@ -2092,6 +2094,9 @@ void drm_atomic_helper_swap_state(struct drm_atomic_state *state,
 		state->planes[i].state = old_plane_state;
 		plane->state = new_plane_state;
 	}
+
+	__for_each_private_obj(state, obj, obj_state, i, funcs)
+		funcs->swap_state(obj, &state->private_objs[i].obj_state);
 }
 EXPORT_SYMBOL(drm_atomic_helper_swap_state);
 

include/drm/drm_atomic.h

@@ -154,6 +154,53 @@ struct __drm_connnectors_state {
 	struct drm_connector_state *state, *old_state, *new_state;
 };
 
+/**
+ * struct drm_private_state_funcs - atomic state functions for private objects
+ *
+ * These hooks are used by atomic helpers to create, swap and destroy states of
+ * private objects. The structure itself is used as a vtable to identify the
+ * associated private object type. Each private object type that needs to be
+ * added to the atomic states is expected to have an implementation of these
+ * hooks and pass a pointer to it's drm_private_state_funcs struct to
+ * drm_atomic_get_private_obj_state().
+ */
+struct drm_private_state_funcs {
+	/**
+	 * @duplicate_state:
+	 *
+	 * Duplicate the current state of the private object and return it. It
+	 * is an error to call this before obj->state has been initialized.
+	 *
+	 * RETURNS:
+	 *
+	 * Duplicated atomic state or NULL when obj->state is not
+	 * initialized or allocation failed.
+	 */
+	void *(*duplicate_state)(struct drm_atomic_state *state, void *obj);
+
+	/**
+	 * @swap_state:
+	 *
+	 * This function swaps the existing state of a private object @obj with
+	 * it's newly created state, the pointer to which is passed as
+	 * @obj_state_ptr.
+	 */
+	void (*swap_state)(void *obj, void **obj_state_ptr);
+
+	/**
+	 * @destroy_state:
+	 *
+	 * Frees the private object state created with @duplicate_state.
+	 */
+	void (*destroy_state)(void *obj_state);
+};
+
+struct __drm_private_objs_state {
+	void *obj;
+	void *obj_state;
+	const struct drm_private_state_funcs *funcs;
+};
+
 /**
  * struct drm_atomic_state - the global state object for atomic updates
  * @ref: count of all references to this state (will not be freed until zero)
@@ -164,6 +211,8 @@ struct __drm_connnectors_state {
  * @crtcs: pointer to array of CRTC pointers
  * @num_connector: size of the @connectors and @connector_states arrays
  * @connectors: pointer to array of structures with per-connector data
+ * @num_private_objs: size of the @private_objs array
+ * @private_objs: pointer to array of private object pointers
  * @acquire_ctx: acquire context for this atomic modeset state update
  */
 struct drm_atomic_state {
@@ -176,6 +225,8 @@ struct drm_atomic_state {
 	struct __drm_crtcs_state *crtcs;
 	int num_connector;
 	struct __drm_connnectors_state *connectors;
+	int num_private_objs;
+	struct __drm_private_objs_state *private_objs;
 
 	struct drm_modeset_acquire_ctx *acquire_ctx;
 
@@ -268,6 +319,11 @@ int drm_atomic_connector_set_property(struct drm_connector *connector,
 		struct drm_connector_state *state, struct drm_property *property,
 		uint64_t val);
 
+void * __must_check
+drm_atomic_get_private_obj_state(struct drm_atomic_state *state,
+			      void *obj,
+			      const struct drm_private_state_funcs *funcs);
+
 /**
  * drm_atomic_get_existing_crtc_state - get crtc state, if it exists
  * @state: global atomic state object
@@ -752,6 +808,45 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
 	     (__i)++)							\
 		for_each_if (plane)
 
+/**
+ * __for_each_private_obj - iterate over all private objects
+ * @__state: &struct drm_atomic_state pointer
+ * @obj: private object iteration cursor
+ * @obj_state: private object state iteration cursor
+ * @__i: int iteration cursor, for macro-internal use
+ * @__funcs: &struct drm_private_state_funcs iteration cursor
+ *
+ * This macro iterates over the array containing private object data in atomic
+ * state
+ */
+#define __for_each_private_obj(__state, obj, obj_state, __i, __funcs)	\
+	for ((__i) = 0;							\
+	     (__i) < (__state)->num_private_objs &&			\
+	     ((obj) = (__state)->private_objs[__i].obj,			\
+	      (__funcs) = (__state)->private_objs[__i].funcs,		\
+	      (obj_state) = (__state)->private_objs[__i].obj_state,	\
+	      1);							\
+	     (__i)++)							\
+
+/**
+ * for_each_private_obj - iterate over a specify type of private object
+ * @__state: &struct drm_atomic_state pointer
+ * @obj_funcs: &struct drm_private_state_funcs function table to filter
+ * 	private objects
+ * @obj: private object iteration cursor
+ * @obj_state: private object state iteration cursor
+ * @__i: int iteration cursor, for macro-internal use
+ * @__funcs: &struct drm_private_state_funcs iteration cursor
+ *
+ * This macro iterates over the private objects state array while filtering the
+ * objects based on the vfunc table that is passed as @obj_funcs. New macros
+ * can be created by passing in the vfunc table associated with a specific
+ * private object.
+ */
+#define for_each_private_obj(__state, obj_funcs, obj, obj_state, __i, __funcs)	\
+	__for_each_private_obj(__state, obj, obj_state, __i, __funcs)		\
+		for_each_if (__funcs == obj_funcs)
+
 /**
  * drm_atomic_crtc_needs_modeset - compute combined modeset need
  * @state: &drm_crtc_state for the CRTC