Message-Id: <1476975005-30441-5-git-send-email-gustavo@padovan.org>
Date:   Thu, 20 Oct 2016 12:50:05 -0200
From:   Gustavo Padovan <gustavo@...ovan.org>
To:     dri-devel@...ts.freedesktop.org
Cc:     linux-kernel@...r.kernel.org, Daniel Stone <daniels@...labora.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Rob Clark <robdclark@...il.com>,
        Greg Hackmann <ghackmann@...gle.com>,
        John Harrison <John.C.Harrison@...el.com>,
        laurent.pinchart@...asonboard.com, seanpaul@...gle.com,
        marcheu@...gle.com, m.chehab@...sung.com,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Gustavo Padovan <gustavo.padovan@...labora.co.uk>
Subject: [PATCH v5 4/4] drm/fence: add out-fences support

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

Support DRM out-fences by creating a sync_file with a fence for each CRTC
that sets the OUT_FENCE_PTR property.

We use the out_fence pointer received in the OUT_FENCE_PTR prop to send
the sync_file fd back to userspace.

The sync_file and fd are allocated/created before commit, but the
fd_install operation only happens after we know that commit succeed.

In case of error userspace should receive a fd number of -1.

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

v3: Comments by Daniel Vetter:
	- create DRM_MODE_ATOMIC_EVENT_MASK
	- userspace should fill out_fences_ptr with the crtc_ids for which
	it wants fences back.

v4: Create OUT_FENCE_PTR properties and remove old approach.

Signed-off-by: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
---
 drivers/gpu/drm/drm_atomic.c | 116 ++++++++++++++++++++++++++++++++++---------
 drivers/gpu/drm/drm_crtc.c   |   8 +++
 include/drm/drm_crtc.h       |  19 +++++++
 3 files changed, 119 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index b3284b2..07775fc 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -490,6 +490,8 @@ int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
 					&replaced);
 		state->color_mgmt_changed |= replaced;
 		return ret;
+	} else if (property == config->prop_out_fence_ptr) {
+		state->out_fence_ptr = u64_to_user_ptr(val);
 	} else if (crtc->funcs->atomic_set_property)
 		return crtc->funcs->atomic_set_property(crtc, state, property, val);
 	else
@@ -532,6 +534,8 @@ drm_atomic_crtc_get_property(struct drm_crtc *crtc,
 		*val = (state->ctm) ? state->ctm->base.id : 0;
 	else if (property == config->gamma_lut_property)
 		*val = (state->gamma_lut) ? state->gamma_lut->base.id : 0;
+	else if (property == config->prop_out_fence_ptr)
+		*val = 0;
 	else if (crtc->funcs->atomic_get_property)
 		return crtc->funcs->atomic_get_property(crtc, state, property, val);
 	else
@@ -1474,11 +1478,9 @@ EXPORT_SYMBOL(drm_atomic_nonblocking_commit);
  */
 
 static struct drm_pending_vblank_event *create_vblank_event(
-		struct drm_device *dev, struct drm_file *file_priv,
-		struct fence *fence, uint64_t user_data)
+		struct drm_device *dev, uint64_t user_data)
 {
 	struct drm_pending_vblank_event *e = NULL;
-	int ret;
 
 	e = kzalloc(sizeof *e, GFP_KERNEL);
 	if (!e)
@@ -1488,17 +1490,6 @@ static struct drm_pending_vblank_event *create_vblank_event(
 	e->event.base.length = sizeof(e->event);
 	e->event.user_data = user_data;
 
-	if (file_priv) {
-		ret = drm_event_reserve_init(dev, file_priv, &e->base,
-					     &e->event.base);
-		if (ret) {
-			kfree(e);
-			return NULL;
-		}
-	}
-
-	e->base.fence = fence;
-
 	return e;
 }
 
@@ -1603,6 +1594,40 @@ void drm_atomic_clean_old_fb(struct drm_device *dev,
 }
 EXPORT_SYMBOL(drm_atomic_clean_old_fb);
 
+static int crtc_setup_out_fence(struct drm_crtc *crtc,
+				struct drm_crtc_state *crtc_state,
+				struct drm_out_fence_state *fence_state)
+{
+	struct fence *fence;
+
+	fence_state->fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fence_state->fd < 0) {
+		return fence_state->fd;
+	}
+
+	fence_state->out_fence_ptr = crtc_state->out_fence_ptr;
+	crtc_state->out_fence_ptr = NULL;
+
+	if (put_user(fence_state->fd, fence_state->out_fence_ptr))
+		return -EFAULT;
+
+	fence = kzalloc(sizeof(*fence), GFP_KERNEL);
+	if (!fence)
+		return -ENOMEM;
+
+	fence_init(fence, &drm_crtc_fence_ops, &crtc->fence_lock,
+		   crtc->fence_context, ++crtc->fence_seqno);
+
+	fence_state->sync_file = sync_file_create(fence);
+	if(!fence_state->sync_file) {
+		fence_put(fence);
+		return -ENOMEM;
+	}
+
+	crtc_state->event->base.fence = fence_get(fence);
+	return 0;
+}
+
 int drm_mode_atomic_ioctl(struct drm_device *dev,
 			  void *data, struct drm_file *file_priv)
 {
@@ -1617,9 +1642,10 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
 	struct drm_plane *plane;
 	struct drm_crtc *crtc;
 	struct drm_crtc_state *crtc_state;
+	struct drm_out_fence_state *fence_state;
 	unsigned plane_mask;
 	int ret = 0;
-	unsigned int i, j;
+	unsigned int i, j, fence_idx = 0;
 
 	/* disallow for drivers not supporting atomic: */
 	if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
@@ -1734,12 +1760,19 @@ retry:
 		drm_mode_object_unreference(obj);
 	}
 
-	if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
-		for_each_crtc_in_state(state, crtc, crtc_state, i) {
+	fence_state = kcalloc(dev->mode_config.num_crtc, sizeof(*fence_state),
+			      GFP_KERNEL);
+	if (!fence_state) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	for_each_crtc_in_state(state, crtc, crtc_state, i) {
+		if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT ||
+		    crtc_state->out_fence_ptr) {
 			struct drm_pending_vblank_event *e;
 
-			e = create_vblank_event(dev, file_priv, NULL,
-						arg->user_data);
+			e = create_vblank_event(dev, arg->user_data);
 			if (!e) {
 				ret = -ENOMEM;
 				goto out;
@@ -1747,6 +1780,28 @@ retry:
 
 			crtc_state->event = e;
 		}
+
+		if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
+			struct drm_pending_vblank_event *e = crtc_state->event;
+
+			if (!file_priv)
+				continue;
+
+			ret = drm_event_reserve_init(dev, file_priv, &e->base,
+						     &e->event.base);
+			if (ret) {
+				kfree(e);
+				crtc_state->event = NULL;
+				goto out;
+			}
+		}
+
+		if (crtc_state->out_fence_ptr) {
+			ret = crtc_setup_out_fence(crtc, crtc_state,
+						   &fence_state[fence_idx++]);
+			if (ret)
+				goto out;
+		}
 	}
 
 	if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) {
@@ -1761,24 +1816,37 @@ retry:
 		ret = drm_atomic_commit(state);
 	}
 
+	for (i = 0; i < fence_idx; i++)
+		fd_install(fence_state[i].fd, fence_state[i].sync_file->file);
+
 out:
 	drm_atomic_clean_old_fb(dev, plane_mask, ret);
 
-	if (ret && arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
+	for_each_crtc_in_state(state, crtc, crtc_state, i) {
 		/*
 		 * TEST_ONLY and PAGE_FLIP_EVENT are mutually exclusive,
 		 * if they weren't, this code should be called on success
 		 * for TEST_ONLY too.
 		 */
+		if (ret && crtc_state->event)
+			drm_event_cancel_free(dev, &crtc_state->event->base);
+	}
 
-		for_each_crtc_in_state(state, crtc, crtc_state, i) {
-			if (!crtc_state->event)
-				continue;
+	if (ret && fence_state) {
+		for (i = 0; i < fence_idx; i++) {
+			if (fence_state[i].fd >= 0)
+				put_unused_fd(fence_state[i].fd);
+			if (fence_state[i].sync_file)
+				fput(fence_state[i].sync_file->file);
 
-			drm_event_cancel_free(dev, &crtc_state->event->base);
+			/* If this fails, there's not much we can do about it */
+			if (put_user(-1, fence_state->out_fence_ptr))
+				DRM_ERROR("Couldn't clear out_fence_ptr\n");
 		}
 	}
 
+	kfree(fence_state);
+
 	if (ret == -EDEADLK) {
 		drm_atomic_state_clear(state);
 		drm_modeset_backoff(&ctx);
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index b99090f..40bce97 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -274,6 +274,8 @@ int drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *crtc,
 	if (drm_core_check_feature(dev, DRIVER_ATOMIC)) {
 		drm_object_attach_property(&crtc->base, config->prop_active, 0);
 		drm_object_attach_property(&crtc->base, config->prop_mode_id, 0);
+		drm_object_attach_property(&crtc->base,
+					   config->prop_out_fence_ptr, 0);
 	}
 
 	return 0;
@@ -434,6 +436,12 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)
 		return -ENOMEM;
 	dev->mode_config.prop_in_fence_fd = prop;
 
+	prop = drm_property_create_range(dev, DRM_MODE_PROP_ATOMIC,
+			"OUT_FENCE_PTR", 0, U64_MAX);
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.prop_out_fence_ptr = prop;
+
 	prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC,
 			"CRTC_ID", DRM_MODE_OBJECT_CRTC);
 	if (!prop)
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 657a33a..b898604 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -165,6 +165,8 @@ struct drm_crtc_state {
 	struct drm_property_blob *ctm;
 	struct drm_property_blob *gamma_lut;
 
+	u64 __user *out_fence_ptr;
+
 	/**
 	 * @event:
 	 *
@@ -748,6 +750,18 @@ static inline struct drm_crtc *fence_to_crtc(struct fence *fence)
 }
 
 /**
+ * struct drm_out_fence_state - store out_fence data for install and clean up
+ * @out_fence_ptr: user pointer to store the fence fd in.
+ * @sync_file: sync_file related to the out_fence
+ * @fd: file descriptor to installed on the sync_file.
+ */
+struct drm_out_fence_state {
+	u64 __user *out_fence_ptr;
+	struct sync_file *sync_file;
+	int fd;
+};
+
+/*
  * 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
@@ -1230,6 +1244,11 @@ struct drm_mode_config {
 	 */
 	struct drm_property *prop_in_fence_fd;
 	/**
+	 * @prop_out_fence_ptr: Sync File fd pointer representing the
+	 * outgoing fences for a CRTC.
+	 */
+	struct drm_property *prop_out_fence_ptr;
+	/**
 	 * @prop_crtc_id: Default atomic plane property to specify the
 	 * &drm_crtc.
 	 */
-- 
2.5.5

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