This IOCTL provides a mechanism for userspace to trigger a sync object
directly. There are other ways that userspace can trigger a syncobj
such as submitting a dummy batch somewhere or hanging on to a triggered
sync_file and doing an import. This just provides an easy way to
manually trigger the sync object without weird hacks.
The motivation for this IOCTL is Vulkan fences. Vulkan lets you create
a fence already in the signaled state so that you can wait on it
immediatly without stalling. We could also handle this with a new
create flag to ask the driver to create a syncobj that is already
signaled but the IOCTL seemed a bit cleaner and more generic.
v2:
- Take an array of sync objects (Dave Airlie)
v3:
- Throw -EINVAL if pad != 0
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This just resets the dma_fence to NULL so it looks like it's never been
signaled. This will be useful once we add the new wait API for allowing
wait on "submit and signal" behavior.
v2:
- Take an array of sync objects (Dave Airlie)
v3:
- Throw -EINVAL if pad != 0
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Christian König <christian.koenig@amd.com> (v1)
Signed-off-by: Dave Airlie <airlied@redhat.com>
The wait ioctl has a bunch of code to read an syncobj handle array from
userspace and turn it into an array of syncobj pointers. We're about to
add two new IOCTLs which will need to work with arrays of syncobj
handles so let's make some helpers.
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Vulkan VkFence semantics require that the application be able to perform
a CPU wait on work which may not yet have been submitted. This is
perfectly safe because the CPU wait has a timeout which will get
triggered eventually if no work is ever submitted. This behavior is
advantageous for multi-threaded workloads because, so long as all of the
threads agree on what fences to use up-front, you don't have the extra
cross-thread synchronization cost of thread A telling thread B that it
has submitted its dependent work and thread B is now free to wait.
Within a single process, this can be implemented in the userspace driver
by doing exactly the same kind of tracking the app would have to do
using posix condition variables or similar. However, in order for this
to work cross-process (as is required by VK_KHR_external_fence), we need
to handle this in the kernel.
This commit adds a WAIT_FOR_SUBMIT flag to DRM_IOCTL_SYNCOBJ_WAIT which
instructs the IOCTL to wait for the syncobj to have a non-null fence and
then wait on the fence. Combined with DRM_IOCTL_SYNCOBJ_RESET, you can
easily get the Vulkan behavior.
v2:
- Fix a bug in the invalid syncobj error path
- Unify the wait-all and wait-any cases
v3:
- Unify the timeout == 0 case a bit with the timeout > 0 case
- Use wait_event_interruptible_timeout
v4:
- Use proxy fence
v5:
- Revert to a combination of v2 and v3
- Don't use proxy fences
- Don't use wait_event_interruptible_timeout because it just adds an
extra layer of callbacks
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This requests that the driver create the sync object such that it
already has a signaled dma_fence attached. Because we don't need
anything in particular (just something signaled), we use a dummy null
fence. This is useful for Vulkan which has a similar flag that can be
passed to vkCreateFence.
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
It is useful in certain circumstances to know when the fence is replaced
in a syncobj. Specifically, it may be useful to know when the fence
goes from NULL to something valid. This does make syncobj_replace_fence
a little more expensive because it has to take a lock but, in the common
case where there is no callback list, it spends a very short amount of
time inside the lock.
v2:
- Don't lock in drm_syncobj_fence_get. We only really need to lock
around fence_replace to make the callback work.
v3:
- Fix the cb_list comment to make kbuild happy
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This interface will allow sync object to be used to back
Vulkan fences. This API is pretty much the vulkan fence waiting
API, and I've ported the code from amdgpu.
v2: accept relative timeout, pass remaining time back
to userspace.
v3: return to absolute timeouts.
v4: absolute zero = poll,
rewrite any/all code to have same operation for arrays
return -EINVAL for 0 fences.
v4.1: fixup fences allocation check, use u64_to_user_ptr
v5: move to sec/nsec, and use timespec64 for calcs.
v6: use -ETIME and drop the out status flag. (-ETIME
is suggested by ickle, I can feel a shed painting)
v7: talked to Daniel/Arnd, use ktime and ns everywhere.
v8: be more careful in the timeout calculations
use uint32_t for counter variables so we don't overflow
graciously handle -ENOINT being returned from dma_fence_wait_timeout
Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
The atomic exchange operation in drm_syncobj_replace_fence is sufficient
for the case where it races with itself. However, if you have a race
between a replace_fence and dma_fence_get(syncobj->fence), you may end
up with the entire replace_fence happening between the point in time
where the one thread gets the syncobj->fence pointer and when it calls
dma_fence_get() on it. If this happens, then the reference may be
dropped before we get a chance to get a new one. The new helper uses
dma_fence_get_rcu_safe to get rid of the race.
This is also needed because it allows us to do a bit more than just get
a reference in drm_syncobj_fence_get should we wish to do so.
v2:
- RCU isn't that scary
- Call rcu_read_lock/unlock
- Don't rename fence to _fence
- Make the helper static inline
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Acked-by: Christian König <christian.koenig@amd.com> (v1)
Signed-off-by: Dave Airlie <airlied@redhat.com>
The function has far more in common with drm_syncobj_find than with
any in the get/put functions.
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Acked-by: Christian König <christian.koenig@amd.com> (v1)
Signed-off-by: Dave Airlie <airlied@redhat.com>
I need this to be able to apply the deferred fbdev setup patches, I
need the relevant prep work that landed through the drm-intel tree.
Also squash in conflict fixup from Laurent Pinchart.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
the drm_file parameter is unused, so remove it.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Airlie <airlied@redhat.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This interface allows importing the fence from a sync_file into
an existing drm sync object, or exporting the fence attached to
an existing drm sync object into a new sync file object.
This should only be used to interact with sync files where necessary.
v1.1: fence put fixes (Chris), drop fence from ioctl names (Chris)
fixup for new fence replace API.
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Sync objects are new toplevel drm object, that contain a
pointer to a fence. This fence can be updated via command
submission ioctls via drivers.
There is also a generic wait obj API modelled on the vulkan
wait API (with code modelled on some amdgpu code).
These objects can be converted to an opaque fd that can be
passes between processes.
v2: rename reference/unreference to put/get (Chris)
fix leaked reference (David Zhou)
drop mutex in favour of cmpxchg (Chris)
v3: cleanups from danvet, rebase on drm_fops rename
check fd_flags is 0 in ioctls.
v4: export find/free, change replace fence to take a
syncobj. In order to support lookup first, replace
later semantics which seem in the end to be cleaner.
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Jason Ekstrand