linux/drivers/gpu/drm/drm_syncobj.c, branch v4.14

drm/syncobj: Add a signal ioctl (v3)

2017-08-29T00:16:25Z

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 Signed-off-by: Dave Airlie

drm/syncobj: Add a reset ioctl (v3)

2017-08-29T00:16:19Z

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 Reviewed-by: Christian König (v1) Signed-off-by: Dave Airlie

drm/syncobj: Add a syncobj_array_find helper

2017-08-28T20:28:23Z

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 Signed-off-by: Dave Airlie

drm/syncobj: Allow wait for submit and signal behavior (v5)

2017-08-28T20:28:17Z

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 Cc: Dave Airlie Cc: Chris Wilson Cc: Christian König Signed-off-by: Dave Airlie

drm/syncobj: Add a CREATE_SIGNALED flag

2017-08-28T20:27:41Z

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 Signed-off-by: Dave Airlie

drm/syncobj: Add a callback mechanism for replace_fence (v3)

2017-08-28T20:26:42Z

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 Signed-off-by: Dave Airlie

drm/syncobj: add sync obj wait interface. (v8)

2017-08-28T20:26:32Z

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 Reviewed-by: Jason Ekstrand Acked-by: Christian König Signed-off-by: Dave Airlie

drm/syncobj: Add a race-free drm_syncobj_fence_get helper (v2)

2017-08-28T20:20:30Z

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 Acked-by: Christian König (v1) Signed-off-by: Dave Airlie

drm/syncobj: Rename fence_get to find_fence

2017-08-28T20:17:37Z

The function has far more in common with drm_syncobj_find than with any in the get/put functions. Signed-off-by: Jason Ekstrand Acked-by: Christian König (v1) Signed-off-by: Dave Airlie

Merge airlied/drm-next into drm-misc-next

2017-07-26T11:43:33Z

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