[RFC v2 8/8] drm/fence: add out-fences support

[Gustavo Padovan <gustavo@padovan.org>]

From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

Support DRM out-fences creating a sync_file with a fence for each crtc
update with the DRM_MODE_ATOMIC_OUT_FENCE flag.

We then send an struct drm_out_fences array with the out-fences fds back in
the drm_atomic_ioctl() as an out arg in the out_fences_ptr field.

struct drm_out_fences {
	__u32   crtc_id;
	__u32   fd;
};

v2: Comment by Rob Clark:
	- Squash commit that adds DRM_MODE_ATOMIC_OUT_FENCE flag here.

    Comment by Daniel Vetter:
	- Add clean up code for out_fences

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
---
 drivers/gpu/drm/drm_atomic.c | 163 +++++++++++++++++++++++++++++++++++++++++--
 include/drm/drm_crtc.h       |  10 +++
 include/uapi/drm/drm_mode.h  |  11 ++-
 3 files changed, 179 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 5f9d434..06c6007 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -1566,6 +1566,133 @@ void drm_atomic_clean_old_fb(struct drm_device *dev,
 }
 EXPORT_SYMBOL(drm_atomic_clean_old_fb);
 
+static struct drm_out_fence_state *get_out_fence(struct drm_device *dev,
+						 struct drm_atomic_state *state,
+						 uint32_t __user *out_fences_ptr,
+						 uint64_t count_out_fences,
+						 uint64_t user_data)
+{
+	struct drm_crtc *crtc;
+	struct drm_crtc_state *crtc_state;
+	struct drm_out_fences *out_fences;
+	struct drm_out_fence_state *fence_state;
+	int num_fences = 0;
+	int i, ret;
+
+	if (count_out_fences > dev->mode_config.num_crtc)
+		return ERR_PTR(-EINVAL);
+
+	out_fences = kcalloc(count_out_fences, sizeof(*out_fences),
+			     GFP_KERNEL);
+	if (!out_fences)
+		return ERR_PTR(-ENOMEM);
+
+	fence_state = kcalloc(count_out_fences, sizeof(*fence_state),
+			     GFP_KERNEL);
+	if (!fence_state) {
+		kfree(out_fences);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	for (i = 0 ; i < count_out_fences ; i++)
+		fence_state[i].fd = -1;
+
+	for_each_crtc_in_state(state, crtc, crtc_state, i) {
+		struct drm_pending_vblank_event *e;
+		struct fence *fence;
+		char name[32];
+
+		fence = kzalloc(sizeof(*fence), GFP_KERNEL);
+		if (!fence) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		fence_init(fence, &drm_crtc_fence_ops, &crtc->fence_lock,
+			   crtc->fence_context, crtc->fence_seqno);
+
+		snprintf(name, sizeof(name), "crtc-%d_%lu",
+			 drm_crtc_index(crtc), crtc->fence_seqno++);
+
+		fence_state[i].fd = get_unused_fd_flags(O_CLOEXEC);
+		if (fence_state[i].fd < 0) {
+			fence_put(fence);
+			ret = fence_state[i].fd;
+			goto out;
+		}
+
+		fence_state[i].sync_file = sync_file_create(name, fence);
+		if(!fence_state[i].sync_file) {
+			fence_put(fence);
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		if (crtc_state->event) {
+			crtc_state->event->base.fence = fence;
+		} else {
+			e = create_vblank_event(dev, NULL, fence, user_data);
+			if (!e) {
+				ret = -ENOMEM;
+				goto out;
+			}
+
+			crtc_state->event = e;
+		}
+
+		out_fences[num_fences].crtc_id = crtc->base.id;
+		out_fences[num_fences].fd = fence_state[i].fd;
+		num_fences++;
+	}
+
+	if (copy_to_user(out_fences_ptr, out_fences,
+			 num_fences * sizeof(*out_fences))) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	kfree(out_fences);
+
+	return fence_state;
+
+out:
+	for (i = 0 ; i < count_out_fences ; i++) {
+		if (fence_state[i].sync_file)
+			sync_file_put(fence_state[i].sync_file);
+		if (fence_state[i].fd >= 0)
+			put_unused_fd(fence_state[i].fd);
+	}
+
+	kfree(fence_state);
+	kfree(out_fences);
+
+	return ERR_PTR(ret);
+}
+
+static void install_out_fence(uint64_t count_out_fences,
+			      struct drm_out_fence_state *state)
+{
+	int i;
+
+	for (i = 0 ; i < count_out_fences ; i++) {
+		if (state[i].sync_file)
+			sync_file_install(state[i].sync_file, state[i].fd);
+	}
+}
+
+static void release_out_fence(uint64_t count_out_fences,
+			      struct drm_out_fence_state *state)
+{
+	int i;
+
+	for (i = 0 ; i < count_out_fences ; i++) {
+		if (state->sync_file)
+			sync_file_put(state->sync_file);
+		if (state->fd >= 0)
+			put_unused_fd(state->fd);
+	}
+}
+
 int drm_mode_atomic_ioctl(struct drm_device *dev,
 			  void *data, struct drm_file *file_priv)
 {
@@ -1574,12 +1701,14 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 	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);
+	uint32_t __user *out_fences_ptr = (uint32_t __user *)(unsigned long)(arg->out_fences_ptr);
 	unsigned int copied_objs, copied_props;
 	struct drm_atomic_state *state;
 	struct drm_modeset_acquire_ctx ctx;
 	struct drm_plane *plane;
 	struct drm_crtc *crtc;
 	struct drm_crtc_state *crtc_state;
+	struct drm_out_fence_state *fence_state = NULL;
 	unsigned plane_mask;
 	int ret = 0;
 	unsigned int i, j;
@@ -1605,9 +1734,13 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 			!dev->mode_config.async_page_flip)
 		return -EINVAL;
 
+	if ((arg->flags & DRM_MODE_ATOMIC_OUT_FENCE) && !arg->count_out_fences)
+		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))
+			(arg->flags & (DRM_MODE_PAGE_FLIP_EVENT
+			 | DRM_MODE_ATOMIC_OUT_FENCE)))
 		return -EINVAL;
 
 	drm_modeset_acquire_init(&ctx, 0);
@@ -1699,16 +1832,30 @@ retry:
 		}
 	}
 
+	if (arg->flags & DRM_MODE_ATOMIC_OUT_FENCE) {
+		fence_state = get_out_fence(dev, state, out_fences_ptr,
+					    arg->count_out_fences,
+					    arg->user_data);
+		if (IS_ERR(fence_state)) {
+			ret = PTR_ERR(fence_state);
+			goto out;
+		}
+	}
+
 	if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) {
 		/*
 		 * Unlike commit, check_only does not clean up state.
 		 * Below we call drm_atomic_state_free for it.
 		 */
 		ret = drm_atomic_check_only(state);
-	} else if (arg->flags & DRM_MODE_ATOMIC_NONBLOCK) {
-		ret = drm_atomic_async_commit(state);
 	} else {
-		ret = drm_atomic_commit(state);
+		if (arg->flags & DRM_MODE_ATOMIC_OUT_FENCE)
+			install_out_fence(arg->count_out_fences, fence_state);
+
+		if (arg->flags & DRM_MODE_ATOMIC_NONBLOCK)
+			ret = drm_atomic_async_commit(state);
+		else
+			ret = drm_atomic_commit(state);
 	}
 
 out:
@@ -1729,6 +1876,14 @@ out:
 		}
 	}
 
+	if ((arg->flags & DRM_MODE_ATOMIC_OUT_FENCE) &&
+	    !IS_ERR_OR_NULL(fence_state)) {
+		if (ret)
+			release_out_fence(arg->count_out_fences, fence_state);
+
+		kfree(fence_state);
+	}
+
 	if (ret == -EDEADLK) {
 		drm_atomic_state_clear(state);
 		drm_modeset_backoff(&ctx);
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index d8c32c8..5f7c272 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -798,6 +798,16 @@ static inline struct drm_crtc *fence_to_crtc(struct fence *fence)
 }
 
 /**
+ * struct drm_out_fence_state - store out_fence data for clean up
+ * @sync_file: sync_file related to the out_fence
+ * @fd: file descriptor to installed on the sync_file.
+ */
+struct drm_out_fence_state {
+	struct sync_file *sync_file;
+	int fd;
+};
+
+/**
  * struct drm_connector_state - mutable connector state
  * @connector: backpointer to the connector
  * @crtc: CRTC to connect connector to, NULL if disabled
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 7a7856e..4cdcd22 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -582,13 +582,20 @@ struct drm_mode_destroy_dumb {
 #define DRM_MODE_ATOMIC_TEST_ONLY 0x0100
 #define DRM_MODE_ATOMIC_NONBLOCK  0x0200
 #define DRM_MODE_ATOMIC_ALLOW_MODESET 0x0400
+#define DRM_MODE_ATOMIC_OUT_FENCE 0x0800
 
 #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)
+		DRM_MODE_ATOMIC_ALLOW_MODESET |\
+		DRM_MODE_ATOMIC_OUT_FENCE)
+
+struct drm_out_fences {
+	__u32	crtc_id;
+	__u32	fd;
+};
 
 struct drm_mode_atomic {
 	__u32 flags;
@@ -599,6 +606,8 @@ struct drm_mode_atomic {
 	__u64 prop_values_ptr;
 	__u64 reserved;
 	__u64 user_data;
+	__u64 count_out_fences;
+	__u64 out_fences_ptr;
 };
 
 /**
-- 
2.5.5