[PATCH v2 1/1] drm/syncobj: add sideband payload
Lionel Landwerlin
lionel.g.landwerlin at intel.com
Thu Aug 8 10:04:23 UTC 2019
On 08/08/2019 12:42, Lionel Landwerlin wrote:
> On 08/08/2019 12:32, Koenig, Christian wrote:
>> Am 08.08.19 um 11:04 schrieb Lionel Landwerlin:
>>> 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)
>>>
>>> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
>>> Cc: Christian Koenig <Christian.Koenig at amd.com>
>>> Cc: Jason Ekstrand <jason at jlekstrand.net>
>>> Cc: David(ChunMing) Zhou <David1.Zhou at amd.com>
>>> ---
>>> drivers/gpu/drm/drm_internal.h | 2 ++
>>> drivers/gpu/drm/drm_ioctl.c | 3 ++
>>> drivers/gpu/drm/drm_syncobj.c | 63
>>> +++++++++++++++++++++++++++++++---
>>> include/drm/drm_syncobj.h | 9 +++++
>>> include/uapi/drm/drm.h | 5 ++-
>>> 5 files changed, 77 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/drm_internal.h
>>> b/drivers/gpu/drm/drm_internal.h
>>> index 51a2055c8f18..de5267711a7c 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_sideband_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..7fd99533f78f 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_SIDEBAND,
>>> drm_syncobj_sideband_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..66f4f91baa6d 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);
>>> + syncobjs[i]->sideband_payload = 0;
>>> + }
>>> drm_syncobj_array_free(syncobjs, args->count_handles);
>>> @@ -1205,7 +1207,7 @@ drm_syncobj_timeline_signal_ioctl(struct
>>> drm_device *dev, void *data,
>>> if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
>>> return -EOPNOTSUPP;
>>> - if (args->pad != 0)
>>> + if (args->flags != 0)
>>> return -EINVAL;
>>> if (args->count_handles == 0)
>>> @@ -1276,7 +1278,7 @@ int drm_syncobj_query_ioctl(struct drm_device
>>> *dev, void *data,
>>> if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
>>> return -EOPNOTSUPP;
>>> - if (args->pad != 0)
>>> + if (args->flags != 0)
>>> return -EINVAL;
>>> if (args->count_handles == 0)
>>> @@ -1312,15 +1314,68 @@ int drm_syncobj_query_ioctl(struct
>>> drm_device *dev, void *data,
>>> point = dma_fence_is_signaled(last_signaled) ?
>>> last_signaled->seqno :
>>> to_dma_fence_chain(last_signaled)->prev_seqno;
>>> - dma_fence_put(last_signaled);
>>> + dma_fence_put(last_signaled);
>
>
> Whoops, I need to drop this.
>
>
>>> } else {
>>> point = 0;
>>> }
>>> ret = copy_to_user(&points[i], &point, sizeof(uint64_t));
>>> ret = ret ? -EFAULT : 0;
>>> if (ret)
>>> + goto error;
>>> + break;
>>> + }
>>> +
>>> +error:
>>> + drm_syncobj_array_free(syncobjs, args->count_handles);
>>> +
>>> + return ret;
>>> +}
>> Those changes above to drm_syncobj_query now look completely unrelated
>> to me.
>
>
> The diff is really weird indeed but apart from the mistake above it's
> right.
Arg no, it was wrong :(
>
>
>>
>>> +
>>> +int drm_syncobj_sideband_ioctl(struct drm_device *dev, void *data,
>>> + struct drm_file *file_private)
>>> +{
>>> + struct drm_syncobj_timeline_array *args = data;
>>> + struct drm_syncobj **syncobjs;
>>> + uint64_t __user *points = u64_to_user_ptr(args->points);
>>> + uint32_t i;
>>> + int ret;
>>> +
>>> + if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
>>> + return -EOPNOTSUPP;
>>> +
>>> + if (args->flags !=
>>> DRM_SYNCOBJ_TIMELINE_ARRAY_GET_SIDEBAND_PAYLOAD &&
>>> + args->flags !=
>>> DRM_SYNCOBJ_TIMELINE_ARRAY_SET_SIDEBAND_PAYLOAD)
>>> + 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++) {
>>> + switch (args->flags) {
>>> + case DRM_SYNCOBJ_TIMELINE_ARRAY_GET_SIDEBAND_PAYLOAD:
>>> + copy_to_user(&points[i],
>>> &syncobjs[i]->sideband_payload, sizeof(uint64_t));
>>> + ret = ret ? -EFAULT : 0;
>>> + if (ret)
>>> + goto error;
>>> + break;
>>> +
>>> + case DRM_SYNCOBJ_TIMELINE_ARRAY_SET_SIDEBAND_PAYLOAD:
>>> + copy_from_user(&syncobjs[i]->sideband_payload, &points[i],
>>> sizeof(uint64_t));
>>> + ret = ret ? -EFAULT : 0;
>>> + if (ret)
>>> + goto error;
>>> break;
>>> + }
>>> }
>>> +
>>> +error:
>>> 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..b587b8e07547 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;
>>> + /**
>>> + * @sideband_payload: A 64bit side band payload.
>>> + *
>>> + * We use the sideband 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.
>>> + */
>>> + u64 sideband_payload;
>>> };
>>> void drm_syncobj_free(struct kref *kref);
>>> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
>>> index 8a5b2f8f8eb9..dfcbaf603aff 100644
>>> --- a/include/uapi/drm/drm.h
>>> +++ b/include/uapi/drm/drm.h
>>> @@ -782,7 +782,9 @@ struct drm_syncobj_timeline_array {
>>> __u64 handles;
>>> __u64 points;
>>> __u32 count_handles;
>>> - __u32 pad;
>>> + __u32 flags;
>>> +#define DRM_SYNCOBJ_TIMELINE_ARRAY_GET_SIDEBAND_PAYLOAD (0)
>>> +#define DRM_SYNCOBJ_TIMELINE_ARRAY_SET_SIDEBAND_PAYLOAD (1)
>>> };
>>> @@ -946,6 +948,7 @@ 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_SIDEBAND DRM_IOWR(0xCE, struct
>>> drm_syncobj_timeline_array)
>> Maybe better add separate get/set IOCTLs, but just a suggestion.
>>
>> Regards,
>> Christian.
>
>
> Alright, I was worried about polluting the ioctl IDs.
>
>
> Did the new tests on the CTS helped reproduce on your side the issue
> this is solving?
>
>
> Thanks,
>
>
> -Lionel
>
>
>>
>>> /**
>>> * Device specific ioctls should only be in their respective headers
>
>
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