The Vulkan timeline semaphores allow signaling to happen on the point of the timeline without all of the its dependencies to be created.
The current 2 implementations (AMD/Intel) of the Vulkan spec on top of the Linux kernel are using a thread to wait on the dependencies of a given point to materialize and delay actual submission to the kernel driver until the wait completes.
If a binary semaphore is submitted for signaling along the side of a timeline semaphore waiting for completion that means that the drm syncobj associated with that binary semaphore will not have a DMA fence associated with it by the time vkQueueSubmit() returns. This and the fact that a binary semaphore can be signaled and unsignaled as before its DMA fences materialize mean that we cannot just rely on the fence within the syncobj but we also need a sideband payload verifying that the fence in the syncobj matches the last submission from the Vulkan API point of view.
This change adds a sideband payload that is incremented with signaled syncobj when vkQueueSubmit() is called. The next vkQueueSubmit() waiting on a the syncobj will read the sideband payload and wait for a fence chain element with a seqno superior or equal to the sideband payload value to be added into the fence chain and use that fence to trigger the submission on the kernel driver.
v2: Use a separate ioctl to get/set the sideband value (Christian)
v3: Use 2 ioctls for get/set (Christian)
v4: Use a single new ioctl
v5: a bunch of blattant mistakes Store payload atomically (Chris)
Signed-off-by: Lionel Landwerlin lionel.g.landwerlin@intel.com Cc: Christian Koenig Christian.Koenig@amd.com Cc: Jason Ekstrand jason@jlekstrand.net Cc: David(ChunMing) Zhou David1.Zhou@amd.com --- drivers/gpu/drm/drm_internal.h | 2 ++ drivers/gpu/drm/drm_ioctl.c | 3 ++ drivers/gpu/drm/drm_syncobj.c | 58 +++++++++++++++++++++++++++++++++- include/drm/drm_syncobj.h | 9 ++++++ include/uapi/drm/drm.h | 17 ++++++++++ 5 files changed, 88 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h index 51a2055c8f18..e297dfd85019 100644 --- a/drivers/gpu/drm/drm_internal.h +++ b/drivers/gpu/drm/drm_internal.h @@ -208,6 +208,8 @@ int drm_syncobj_timeline_signal_ioctl(struct drm_device *dev, void *data, struct drm_file *file_private); int drm_syncobj_query_ioctl(struct drm_device *dev, void *data, struct drm_file *file_private); +int drm_syncobj_binary_ioctl(struct drm_device *dev, void *data, + struct drm_file *file_private);
/* drm_framebuffer.c */ void drm_framebuffer_print_info(struct drm_printer *p, unsigned int indent, diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index f675a3bb2c88..644d0bc800a4 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -703,6 +703,9 @@ static const struct drm_ioctl_desc drm_ioctls[] = { DRM_RENDER_ALLOW), DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_QUERY, drm_syncobj_query_ioctl, DRM_RENDER_ALLOW), + DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_BINARY, drm_syncobj_binary_ioctl, + DRM_RENDER_ALLOW), + DRM_IOCTL_DEF(DRM_IOCTL_CRTC_GET_SEQUENCE, drm_crtc_get_sequence_ioctl, 0), DRM_IOCTL_DEF(DRM_IOCTL_CRTC_QUEUE_SEQUENCE, drm_crtc_queue_sequence_ioctl, 0), DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATE_LEASE, drm_mode_create_lease_ioctl, DRM_MASTER), diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c index b927e482e554..d2d3a8d1374d 100644 --- a/drivers/gpu/drm/drm_syncobj.c +++ b/drivers/gpu/drm/drm_syncobj.c @@ -1150,8 +1150,10 @@ drm_syncobj_reset_ioctl(struct drm_device *dev, void *data, if (ret < 0) return ret;
- for (i = 0; i < args->count_handles; i++) + for (i = 0; i < args->count_handles; i++) { drm_syncobj_replace_fence(syncobjs[i], NULL); + atomic64_set(&syncobjs[i]->binary_payload, 0); + }
drm_syncobj_array_free(syncobjs, args->count_handles);
@@ -1321,6 +1323,60 @@ int drm_syncobj_query_ioctl(struct drm_device *dev, void *data, if (ret) break; } + + drm_syncobj_array_free(syncobjs, args->count_handles); + + return ret; +} + +int drm_syncobj_binary_ioctl(struct drm_device *dev, void *data, + struct drm_file *file_private) +{ + struct drm_syncobj_binary_array *args = data; + struct drm_syncobj **syncobjs; + u32 __user *access_flags = u64_to_user_ptr(args->access_flags); + u64 __user *values = u64_to_user_ptr(args->values); + u32 i; + int ret; + + if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE)) + return -EOPNOTSUPP; + + if (args->pad != 0) + return -EINVAL; + + if (args->count_handles == 0) + return -EINVAL; + + ret = drm_syncobj_array_find(file_private, + u64_to_user_ptr(args->handles), + args->count_handles, + &syncobjs); + if (ret < 0) + return ret; + + for (i = 0; i < args->count_handles; i++) { + u32 flags; + + if (get_user(flags, &access_flags[i])) { + ret = -EFAULT; + break; + } + + + if (flags & DRM_SYNCOBJ_BINARY_VALUE_READ) { + u64 value = atomic64_read(&syncobjs[i]->binary_payload); + + if (put_user(value, &values[i])) { + ret = -EFAULT; + break; + } + } + + if (flags & DRM_SYNCOBJ_BINARY_VALUE_INC) + atomic64_inc(&syncobjs[i]->binary_payload); + } + drm_syncobj_array_free(syncobjs, args->count_handles);
return ret; diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h index 6cf7243a1dc5..aa76cb3f9107 100644 --- a/include/drm/drm_syncobj.h +++ b/include/drm/drm_syncobj.h @@ -61,6 +61,15 @@ struct drm_syncobj { * @file: A file backing for this syncobj. */ struct file *file; + /** + * @binary_payload: A 64bit payload for binary syncobjs. + * + * We use the payload value to wait on binary syncobj fences to + * materialize. It is a reservation mechanism for the signaler to + * express that at some point in the future a dma fence with the same + * seqno will be put into the syncobj. + */ + atomic64_t binary_payload; };
void drm_syncobj_free(struct kref *kref); diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h index 8a5b2f8f8eb9..78a0a413b788 100644 --- a/include/uapi/drm/drm.h +++ b/include/uapi/drm/drm.h @@ -785,6 +785,22 @@ struct drm_syncobj_timeline_array { __u32 pad; };
+struct drm_syncobj_binary_array { + /* A pointer to an array of u32 syncobj handles. */ + __u64 handles; + /* A pointer to an array of u32 access flags for each handle. */ + __u64 access_flags; + /* The binary value of a syncobj is read before it is incremented. */ +#define DRM_SYNCOBJ_BINARY_VALUE_READ (1u << 0) +#define DRM_SYNCOBJ_BINARY_VALUE_INC (1u << 1) + /* A pointer to an array of u64 values written to by the kernel if the + * handle is flagged for reading. + */ + __u64 values; + /* The length of the 3 arrays above. */ + __u32 count_handles; + __u32 pad; +};
/* Query current scanout sequence number */ struct drm_crtc_get_sequence { @@ -946,6 +962,7 @@ extern "C" { #define DRM_IOCTL_SYNCOBJ_QUERY DRM_IOWR(0xCB, struct drm_syncobj_timeline_array) #define DRM_IOCTL_SYNCOBJ_TRANSFER DRM_IOWR(0xCC, struct drm_syncobj_transfer) #define DRM_IOCTL_SYNCOBJ_TIMELINE_SIGNAL DRM_IOWR(0xCD, struct drm_syncobj_timeline_array) +#define DRM_IOCTL_SYNCOBJ_BINARY DRM_IOWR(0xCE, struct drm_syncobj_binary_array)
/** * Device specific ioctls should only be in their respective headers