drm: Atomic modeset ioctl

The atomic modeset ioctl can be used to push any number of new values
for object properties. The driver can then check the full device
configuration as single unit, and try to apply the changes atomically.

The ioctl simply takes a list of object IDs and property IDs and their
values.

Originally based on a patch from Ville Syrjälä, although it has mutated
(mutilated?) enough since then that you probably shouldn't blame it on
him ;-)

The atomic support is hidden behind the DRM_CLIENT_CAP_ATOMIC cap (to
protect legacy userspace) and drm.atomic module param (for now).

v2: Check for file_priv->atomic to make sure we only allow userspace
in-the-know to use atomic.
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_atomic.c

@@ -56,6 +56,11 @@ drm_atomic_state_alloc(struct drm_device *dev)
 	if (!state)
 		return NULL;
 
+	/* TODO legacy paths should maybe do a better job about
+	 * setting this appropriately?
+	 */
+	state->allow_modeset = true;
+
 	state->num_connector = ACCESS_ONCE(dev->mode_config.num_connector);
 
 	state->crtcs = kcalloc(dev->mode_config.num_crtc,
@@ -1003,6 +1008,22 @@ int drm_atomic_check_only(struct drm_atomic_state *state)
 	if (config->funcs->atomic_check)
 		ret = config->funcs->atomic_check(state->dev, state);
 
+	if (!state->allow_modeset) {
+		for (i = 0; i < ncrtcs; i++) {
+			struct drm_crtc *crtc = state->crtcs[i];
+			struct drm_crtc_state *crtc_state = state->crtc_states[i];
+
+			if (!crtc)
+				continue;
+
+			if (crtc_state->mode_changed) {
+				DRM_DEBUG_KMS("[CRTC:%d] requires full modeset\n",
+					      crtc->base.id);
+				return -EINVAL;
+			}
+		}
+	}
+
 	return ret;
 }
 EXPORT_SYMBOL(drm_atomic_check_only);
@@ -1068,3 +1089,313 @@ int drm_atomic_async_commit(struct drm_atomic_state *state)
 	return config->funcs->atomic_commit(state->dev, state, true);
 }
 EXPORT_SYMBOL(drm_atomic_async_commit);
+
+/*
+ * The big monstor ioctl
+ */
+
+static struct drm_pending_vblank_event *create_vblank_event(
+		struct drm_device *dev, struct drm_file *file_priv, uint64_t user_data)
+{
+	struct drm_pending_vblank_event *e = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->event_lock, flags);
+	if (file_priv->event_space < sizeof e->event) {
+		spin_unlock_irqrestore(&dev->event_lock, flags);
+		goto out;
+	}
+	file_priv->event_space -= sizeof e->event;
+	spin_unlock_irqrestore(&dev->event_lock, flags);
+
+	e = kzalloc(sizeof *e, GFP_KERNEL);
+	if (e == NULL) {
+		spin_lock_irqsave(&dev->event_lock, flags);
+		file_priv->event_space += sizeof e->event;
+		spin_unlock_irqrestore(&dev->event_lock, flags);
+		goto out;
+	}
+
+	e->event.base.type = DRM_EVENT_FLIP_COMPLETE;
+	e->event.base.length = sizeof e->event;
+	e->event.user_data = user_data;
+	e->base.event = &e->event.base;
+	e->base.file_priv = file_priv;
+	e->base.destroy = (void (*) (struct drm_pending_event *)) kfree;
+
+out:
+	return e;
+}
+
+static void destroy_vblank_event(struct drm_device *dev,
+		struct drm_file *file_priv, struct drm_pending_vblank_event *e)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->event_lock, flags);
+	file_priv->event_space += sizeof e->event;
+	spin_unlock_irqrestore(&dev->event_lock, flags);
+	kfree(e);
+}
+
+static int atomic_set_prop(struct drm_atomic_state *state,
+		struct drm_mode_object *obj, struct drm_property *prop,
+		uint64_t prop_value)
+{
+	struct drm_mode_object *ref;
+	int ret;
+
+	if (!drm_property_change_valid_get(prop, prop_value, &ref))
+		return -EINVAL;
+
+	switch (obj->type) {
+	case DRM_MODE_OBJECT_CONNECTOR: {
+		struct drm_connector *connector = obj_to_connector(obj);
+		struct drm_connector_state *connector_state;
+
+		connector_state = drm_atomic_get_connector_state(state, connector);
+		if (IS_ERR(connector_state)) {
+			ret = PTR_ERR(connector_state);
+			break;
+		}
+
+		ret = drm_atomic_connector_set_property(connector,
+				connector_state, prop, prop_value);
+		break;
+	}
+	case DRM_MODE_OBJECT_CRTC: {
+		struct drm_crtc *crtc = obj_to_crtc(obj);
+		struct drm_crtc_state *crtc_state;
+
+		crtc_state = drm_atomic_get_crtc_state(state, crtc);
+		if (IS_ERR(crtc_state)) {
+			ret = PTR_ERR(crtc_state);
+			break;
+		}
+
+		ret = drm_atomic_crtc_set_property(crtc,
+				crtc_state, prop, prop_value);
+		break;
+	}
+	case DRM_MODE_OBJECT_PLANE: {
+		struct drm_plane *plane = obj_to_plane(obj);
+		struct drm_plane_state *plane_state;
+
+		plane_state = drm_atomic_get_plane_state(state, plane);
+		if (IS_ERR(plane_state)) {
+			ret = PTR_ERR(plane_state);
+			break;
+		}
+
+		ret = drm_atomic_plane_set_property(plane,
+				plane_state, prop, prop_value);
+		break;
+	}
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	drm_property_change_valid_put(prop, ref);
+	return ret;
+}
+
+int drm_mode_atomic_ioctl(struct drm_device *dev,
+			  void *data, struct drm_file *file_priv)
+{
+	struct drm_mode_atomic *arg = data;
+	uint32_t __user *objs_ptr = (uint32_t __user *)(unsigned long)(arg->objs_ptr);
+	uint32_t __user *count_props_ptr = (uint32_t __user *)(unsigned long)(arg->count_props_ptr);
+	uint32_t __user *props_ptr = (uint32_t __user *)(unsigned long)(arg->props_ptr);
+	uint64_t __user *prop_values_ptr = (uint64_t __user *)(unsigned long)(arg->prop_values_ptr);
+	unsigned int copied_objs, copied_props;
+	struct drm_atomic_state *state;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_plane *plane;
+	unsigned plane_mask = 0;
+	int ret = 0;
+	unsigned int i, j;
+
+	/* disallow for drivers not supporting atomic: */
+	if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
+		return -EINVAL;
+
+	/* disallow for userspace that has not enabled atomic cap (even
+	 * though this may be a bit overkill, since legacy userspace
+	 * wouldn't know how to call this ioctl)
+	 */
+	if (!file_priv->atomic)
+		return -EINVAL;
+
+	if (arg->flags & ~DRM_MODE_ATOMIC_FLAGS)
+		return -EINVAL;
+
+	if (arg->reserved)
+		return -EINVAL;
+
+	if ((arg->flags & DRM_MODE_PAGE_FLIP_ASYNC) &&
+			!dev->mode_config.async_page_flip)
+		return -EINVAL;
+
+	/* can't test and expect an event at the same time. */
+	if ((arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) &&
+			(arg->flags & DRM_MODE_PAGE_FLIP_EVENT))
+		return -EINVAL;
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+	state = drm_atomic_state_alloc(dev);
+	if (!state)
+		return -ENOMEM;
+
+	state->acquire_ctx = &ctx;
+	state->allow_modeset = !!(arg->flags & DRM_MODE_ATOMIC_ALLOW_MODESET);
+
+retry:
+	copied_objs = 0;
+	copied_props = 0;
+
+	for (i = 0; i < arg->count_objs; i++) {
+		uint32_t obj_id, count_props;
+		struct drm_mode_object *obj;
+
+		if (get_user(obj_id, objs_ptr + copied_objs)) {
+			ret = -EFAULT;
+			goto fail;
+		}
+
+		obj = drm_mode_object_find(dev, obj_id, DRM_MODE_OBJECT_ANY);
+		if (!obj || !obj->properties) {
+			ret = -ENOENT;
+			goto fail;
+		}
+
+		if (obj->type == DRM_MODE_OBJECT_PLANE) {
+			plane = obj_to_plane(obj);
+			plane_mask |= (1 << drm_plane_index(plane));
+			plane->old_fb = plane->fb;
+		}
+
+		if (get_user(count_props, count_props_ptr + copied_objs)) {
+			ret = -EFAULT;
+			goto fail;
+		}
+
+		copied_objs++;
+
+		for (j = 0; j < count_props; j++) {
+			uint32_t prop_id;
+			uint64_t prop_value;
+			struct drm_property *prop;
+
+			if (get_user(prop_id, props_ptr + copied_props)) {
+				ret = -EFAULT;
+				goto fail;
+			}
+
+			prop = drm_property_find(dev, prop_id);
+			if (!prop) {
+				ret = -ENOENT;
+				goto fail;
+			}
+
+			if (get_user(prop_value, prop_values_ptr + copied_props)) {
+				ret = -EFAULT;
+				goto fail;
+			}
+
+			ret = atomic_set_prop(state, obj, prop, prop_value);
+			if (ret)
+				goto fail;
+
+			copied_props++;
+		}
+	}
+
+	if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
+		int ncrtcs = dev->mode_config.num_crtc;
+
+		for (i = 0; i < ncrtcs; i++) {
+			struct drm_crtc_state *crtc_state = state->crtc_states[i];
+			struct drm_pending_vblank_event *e;
+
+			if (!crtc_state)
+				continue;
+
+			e = create_vblank_event(dev, file_priv, arg->user_data);
+			if (!e) {
+				ret = -ENOMEM;
+				goto fail;
+			}
+
+			crtc_state->event = e;
+		}
+	}
+
+	if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) {
+		ret = drm_atomic_check_only(state);
+		/* _check_only() does not free state, unlike _commit() */
+		drm_atomic_state_free(state);
+	} else if (arg->flags & DRM_MODE_ATOMIC_NONBLOCK) {
+		ret = drm_atomic_async_commit(state);
+	} else {
+		ret = drm_atomic_commit(state);
+	}
+
+	/* if succeeded, fixup legacy plane crtc/fb ptrs before dropping
+	 * locks (ie. while it is still safe to deref plane->state).  We
+	 * need to do this here because the driver entry points cannot
+	 * distinguish between legacy and atomic ioctls.
+	 */
+	drm_for_each_plane_mask(plane, dev, plane_mask) {
+		if (ret == 0) {
+			struct drm_framebuffer *new_fb = plane->state->fb;
+			if (new_fb)
+				drm_framebuffer_reference(new_fb);
+			plane->fb = new_fb;
+			plane->crtc = plane->state->crtc;
+		} else {
+			plane->old_fb = NULL;
+		}
+		if (plane->old_fb) {
+			drm_framebuffer_unreference(plane->old_fb);
+			plane->old_fb = NULL;
+		}
+	}
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+
+	return ret;
+
+fail:
+	if (ret == -EDEADLK)
+		goto backoff;
+
+	if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
+		int ncrtcs = dev->mode_config.num_crtc;
+
+		for (i = 0; i < ncrtcs; i++) {
+			struct drm_crtc_state *crtc_state = state->crtc_states[i];
+
+			if (!crtc_state)
+				continue;
+
+			destroy_vblank_event(dev, file_priv, crtc_state->event);
+			crtc_state->event = NULL;
+		}
+	}
+
+	drm_atomic_state_free(state);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+
+	return ret;
+
+backoff:
+	drm_atomic_state_clear(state);
+	drm_modeset_backoff(&ctx);
+
+	goto retry;
+}

drivers/gpu/drm/drm_crtc.c

@@ -4303,7 +4303,7 @@ EXPORT_SYMBOL(drm_mode_connector_update_edid_property);
  * object to which the property is attached has a chance to take it's own
  * reference).
  */
-static bool drm_property_change_valid_get(struct drm_property *property,
+bool drm_property_change_valid_get(struct drm_property *property,
 					 uint64_t value, struct drm_mode_object **ref)
 {
 	int i;
@@ -4365,7 +4365,7 @@ static bool drm_property_change_valid_get(struct drm_property *property,
 	return false;
 }
 
-static void drm_property_change_valid_put(struct drm_property *property,
+void drm_property_change_valid_put(struct drm_property *property,
 		struct drm_mode_object *ref)
 {
 	if (!ref)

drivers/gpu/drm/drm_ioctl.c

@@ -630,6 +630,7 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
 	DRM_IOCTL_DEF(DRM_IOCTL_MODE_OBJ_GETPROPERTIES, drm_mode_obj_get_properties_ioctl, DRM_CONTROL_ALLOW|DRM_UNLOCKED),
 	DRM_IOCTL_DEF(DRM_IOCTL_MODE_OBJ_SETPROPERTY, drm_mode_obj_set_property_ioctl, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
 	DRM_IOCTL_DEF(DRM_IOCTL_MODE_CURSOR2, drm_mode_cursor2_ioctl, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
+	DRM_IOCTL_DEF(DRM_IOCTL_MODE_ATOMIC, drm_mode_atomic_ioctl, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
 };
 
 #define DRM_CORE_IOCTL_COUNT	ARRAY_SIZE( drm_ioctls )

include/drm/drm_crtc.h

@@ -902,7 +902,7 @@ 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
+ * @allow_modeset: allow full modeset
  * @planes: pointer to array of plane pointers
  * @plane_states: pointer to array of plane states pointers
  * @crtcs: pointer to array of CRTC pointers
@@ -914,7 +914,7 @@ struct drm_bridge {
  */
 struct drm_atomic_state {
 	struct drm_device *dev;
-	uint32_t flags;
+	bool allow_modeset : 1;
 	struct drm_plane **planes;
 	struct drm_plane_state **plane_states;
 	struct drm_crtc **crtcs;
@@ -1346,6 +1346,10 @@ extern int drm_mode_create_scaling_mode_property(struct drm_device *dev);
 extern int drm_mode_create_aspect_ratio_property(struct drm_device *dev);
 extern int drm_mode_create_dirty_info_property(struct drm_device *dev);
 extern int drm_mode_create_suggested_offset_properties(struct drm_device *dev);
+extern bool drm_property_change_valid_get(struct drm_property *property,
+					 uint64_t value, struct drm_mode_object **ref);
+extern void drm_property_change_valid_put(struct drm_property *property,
+		struct drm_mode_object *ref);
 
 extern int drm_mode_connector_attach_encoder(struct drm_connector *connector,
 					     struct drm_encoder *encoder);
@@ -1437,6 +1441,8 @@ extern int drm_mode_obj_set_property_ioctl(struct drm_device *dev, void *data,
 extern int drm_mode_plane_set_obj_prop(struct drm_plane *plane,
 				       struct drm_property *property,
 				       uint64_t value);
+extern int drm_mode_atomic_ioctl(struct drm_device *dev,
+				 void *data, struct drm_file *file_priv);
 
 extern void drm_fb_get_bpp_depth(uint32_t format, unsigned int *depth,
 				 int *bpp);

include/uapi/drm/drm.h

@@ -784,6 +784,7 @@ struct drm_prime_handle {
 #define DRM_IOCTL_MODE_OBJ_GETPROPERTIES	DRM_IOWR(0xB9, struct drm_mode_obj_get_properties)
 #define DRM_IOCTL_MODE_OBJ_SETPROPERTY	DRM_IOWR(0xBA, struct drm_mode_obj_set_property)
 #define DRM_IOCTL_MODE_CURSOR2		DRM_IOWR(0xBB, struct drm_mode_cursor2)
+#define DRM_IOCTL_MODE_ATOMIC		DRM_IOWR(0xBC, struct drm_mode_atomic)
 
 /**
  * Device specific ioctls should only be in their respective headers

include/uapi/drm/drm_mode.h

@@ -526,4 +526,27 @@ struct drm_mode_destroy_dumb {
 	uint32_t handle;
 };
 
+/* page-flip flags are valid, plus: */
+#define DRM_MODE_ATOMIC_TEST_ONLY 0x0100
+#define DRM_MODE_ATOMIC_NONBLOCK  0x0200
+#define DRM_MODE_ATOMIC_ALLOW_MODESET 0x0400
+
+#define DRM_MODE_ATOMIC_FLAGS (\
+		DRM_MODE_PAGE_FLIP_EVENT |\
+		DRM_MODE_PAGE_FLIP_ASYNC |\
+		DRM_MODE_ATOMIC_TEST_ONLY |\
+		DRM_MODE_ATOMIC_NONBLOCK |\
+		DRM_MODE_ATOMIC_ALLOW_MODESET)
+
+struct drm_mode_atomic {
+	__u32 flags;
+	__u32 count_objs;
+	__u64 objs_ptr;
+	__u64 count_props_ptr;
+	__u64 props_ptr;
+	__u64 prop_values_ptr;
+	__u64 reserved;
+	__u64 user_data;
+};
+
 #endif