linux-kernel - [PATCH v2] drm/syncobj: Extend EXPORT_SYNC

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Message-ID: <20250327154858.52308-1-robdclark@gmail.com>
Date: Thu, 27 Mar 2025 08:48:57 -0700
From: Rob Clark <robdclark@...il.com>
To: dri-devel@...ts.freedesktop.org
Cc: Christian König <christian.koenig@....com>,
	Dmitry Osipenko <dmitry.osipenko@...labora.com>,
	Rob Clark <robdclark@...omium.org>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Sumit Semwal <sumit.semwal@...aro.org>,
	linux-kernel@...r.kernel.org (open list),
	linux-media@...r.kernel.org (open list:DMA BUFFER SHARING FRAMEWORK:Keyword:\bdma_(?:buf|fence|resv)\b),
	linaro-mm-sig@...ts.linaro.org (moderated list:DMA BUFFER SHARING FRAMEWORK:Keyword:\bdma_(?:buf|fence|resv)\b)
Subject: [PATCH v2] drm/syncobj: Extend EXPORT_SYNC_FILE for timeline syncobjs

From: Rob Clark <robdclark@...omium.org>

Add support for exporting a dma_fence fd for a specific point on a
timeline.  This is needed for vtest/vpipe[1][2] to implement timeline
syncobj support, as it needs a way to turn a point on a timeline back
into a dma_fence fd.  It also closes an odd omission from the syncobj
UAPI.

[1] https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33433
[2] https://gitlab.freedesktop.org/virgl/virglrenderer/-/merge_requests/805

v2: Add DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_TIMELINE

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/gpu/drm/drm_syncobj.c | 18 +++++++++++++-----
 include/uapi/drm/drm.h        |  2 ++
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 4f2ab8a7b50f..bc57d6f1a22e 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -762,7 +762,7 @@ static int drm_syncobj_import_sync_file_fence(struct drm_file *file_private,
 }
 
 static int drm_syncobj_export_sync_file(struct drm_file *file_private,
-					int handle, int *p_fd)
+					int handle, u64 point, int *p_fd)
 {
 	int ret;
 	struct dma_fence *fence;
@@ -772,7 +772,7 @@ static int drm_syncobj_export_sync_file(struct drm_file *file_private,
 	if (fd < 0)
 		return fd;
 
-	ret = drm_syncobj_find_fence(file_private, handle, 0, 0, &fence);
+	ret = drm_syncobj_find_fence(file_private, handle, point, 0, &fence);
 	if (ret)
 		goto err_put_fd;
 
@@ -869,6 +869,9 @@ drm_syncobj_handle_to_fd_ioctl(struct drm_device *dev, void *data,
 				   struct drm_file *file_private)
 {
 	struct drm_syncobj_handle *args = data;
+	unsigned valid_flags = DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_TIMELINE |
+			       DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE;
+	u64 point = 0;
 
 	if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
 		return -EOPNOTSUPP;
@@ -876,13 +879,18 @@ drm_syncobj_handle_to_fd_ioctl(struct drm_device *dev, void *data,
 	if (args->pad)
 		return -EINVAL;
 
-	if (args->flags != 0 &&
-	    args->flags != DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE)
+	if (args->flags != 0 && (args->flags & ~valid_flags))
 		return -EINVAL;
 
+	if (args->flags & DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_TIMELINE)
+		point = args->point;
+
 	if (args->flags & DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE)
 		return drm_syncobj_export_sync_file(file_private, args->handle,
-						    &args->fd);
+						    point, &args->fd);
+
+	if (args->point)
+		return -EINVAL;
 
 	return drm_syncobj_handle_to_fd(file_private, args->handle,
 					&args->fd);
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
index 7fba37b94401..c71a8f4439f2 100644
--- a/include/uapi/drm/drm.h
+++ b/include/uapi/drm/drm.h
@@ -912,6 +912,8 @@ struct drm_syncobj_handle {
 
 	__s32 fd;
 	__u32 pad;
+
+	__u64 point;
 };
 
 struct drm_syncobj_transfer {
-- 
2.49.0