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>

1 files changed, 331 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 57cc68177f09..67f64bd1058f 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/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;
+}