[PATCH 0/9] drm/syncobj: Add full-featured wait support (v2)

[Christian König]

Patches #1-#4 are Acked-by: Christian König <christian.koenig at amd.com>.

Patch #5: NAK, that will break radeon.

On radeon we need the non-default wait or otherwise we can run into a 
situation where we never signal a fence.

The general question is why do you need this?

Patch #6: Yes, please. Patch is Reviewed-by: Christian König 
<christian.koenig at amd.com>.

Patch #7: Already gave my rb on the patch Chris send out earlier.

Patch #8: NAK to the whole approach.

IIRC we discussed a very similar thing during the initial fence bringup 
and also during the fence_array development.

The problem is that you can easily build ring dependencies and so 
deadlocks with it.

I would really prefer an approach which is completely contained inside 
the syncobj code base.

Regards,
Christian.

Am 12.08.2017 um 00:39 schrieb Jason Ekstrand:
> This series does the same thing as my earlier series in that it adds a sync
> object wait interface complete with WAIT_FOR_SUBMIT flag.  While the uapi
> remains unchanged, the guts look a bit different.  Instead of adding a
> callback mechanism to drm_syncobj that fired whenever replace_fence was
> called, it's now using proxy fences.  The drm_syncobj_fence_get still
> returns NULL whenever the sync object is in an unsubmitted state but there
> is a new drm_syncobj_fence_proxy_get which returns either the real fence or
> a proxy fence that will be triggered the next time replace_fence is called
> with a non-NULL replacement.  This does make both drm_syncobj_fence_get and
> drm_syncobj_replace_fence a tiny bit more expensive, but it lets us do it
> all without locking.
>
> This series can be found as a branch here:
>
> https://cgit.freedesktop.org/~jekstrand/linux/log/?h=drm-syncobj-wait-submit-v4
>
> IGT tests for DRM_IOCTL_SYNCOBJ_WAIT and DRM_IOCTL_SYNCOBJ_RESET can be
> found on patchwork here:
>
> https://patchwork.freedesktop.org/series/28666/
>
> Patches to the Intel Vulkan driver to implement VK_KHR_external_fence on
> top of this kernel interface can be found here:
>
> https://cgit.freedesktop.org/~jekstrand/mesa/log/?h=wip/anv-external-fence
>
> Cc: Dave Airlie <airlied at redhat.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Christian König <christian.koenig at amd.com>
>
> Chris Wilson (2):
>    dma-buf/dma-fence: Signal all callbacks from dma_fence_release()
>    dma-buf/dma-fence: Add a mechanism for proxy fences
>
> Dave Airlie (1):
>    drm/syncobj: add sync obj wait interface. (v8)
>
> Jason Ekstrand (6):
>    drm/syncobj: Rename fence_get to find_fence
>    drm/syncobj: Add a race-free drm_syncobj_fence_get helper
>    i915: Add support for drm syncobjs
>    dma-buf/dma-fence: Allow wait_any_timeout without default_wait (v2)
>    drm/syncobj: Add a reset ioctl
>    drm/syncobj: Allow wait for submit and signal behavior (v4)
>
>   drivers/dma-buf/Makefile                   |   4 +-
>   drivers/dma-buf/dma-fence-proxy.c          | 186 +++++++++++++++++++
>   drivers/dma-buf/dma-fence.c                |  34 ++--
>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c     |   2 +-
>   drivers/gpu/drm/drm_internal.h             |   4 +
>   drivers/gpu/drm/drm_ioctl.c                |   4 +
>   drivers/gpu/drm/drm_syncobj.c              | 275 +++++++++++++++++++++++++++--
>   drivers/gpu/drm/i915/i915_drv.c            |   3 +-
>   drivers/gpu/drm/i915/i915_gem_execbuffer.c | 146 ++++++++++++++-
>   include/drm/drm_syncobj.h                  |  15 +-
>   include/linux/dma-fence-proxy.h            |  25 +++
>   include/uapi/drm/drm.h                     |  19 ++
>   include/uapi/drm/i915_drm.h                |  30 +++-
>   13 files changed, 710 insertions(+), 37 deletions(-)
>   create mode 100644 drivers/dma-buf/dma-fence-proxy.c
>   create mode 100644 include/linux/dma-fence-proxy.h
>