Am 07.11.2016 um 04:29 schrieb Michel Dänzer: > On 07/11/16 11:47 AM, Mario Kleiner wrote: >> External clients which import our bo's wait only >> for exclusive dmabuf-fences, not on shared ones, >> so attach fences on exported buffers as exclusive >> ones, if the buffers get imported by an external >> client. >> >> See discussion in thread: >> https://lists.freedesktop.org/archives/dri-devel/2016-October/122370.html >> >> Tested on Intel iGPU + AMD Tonga dGPU as DRI3/Present >> Prime render offload, and with the Tonga standalone as >> primary gpu. >> >> v2: Add a wait for all shared fences before prime export, >> as suggested by Christian Koenig. >> >> v3: - Mark buffer prime_exported in amdgpu_gem_prime_pin, >> so we only use the exclusive fence when exporting a >> bo to external clients like a separate iGPU, but not >> when exporting/importing from/to ourselves as part of >> regular DRI3 fd passing. >> >> - Propagate failure of reservation_object_wait_rcu back >> to caller. >> >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=95472 >> (v1) Tested-by: Mike Lothian <mike at fireburn.co.uk> > FWIW, I think the (v1) is usually added at the end of the line, not at > the beginning. > > [...] > >> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c >> index 7700dc2..c4494d0 100644 >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c >> @@ -81,6 +81,20 @@ int amdgpu_gem_prime_pin(struct drm_gem_object *obj) >> { >> struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj); >> int ret = 0; >> + long lret; >> + >> + /* >> + * Wait for all shared fences to complete before we switch to future >> + * use of exclusive fence on this prime_exported bo. >> + */ >> + lret = reservation_object_wait_timeout_rcu(bo->tbo.resv, true, false, >> + MAX_SCHEDULE_TIMEOUT); >> + if (unlikely(lret < 0)) { >> + DRM_DEBUG_PRIME("Fence wait failed: %li\n", lret); >> + return lret; >> + } >> + >> + bo->prime_exported = true; > We should probably clear bo->prime_exported in amdgpu_gem_prime_unpin. > > Also, I think we should set bo->prime_exported (prime_shared?) in > amdgpu_gem_prime_import_sg_table as well, so that we'll also set > exclusive fences on BOs imported from other GPUs. Yes, really good idea. Additional to that are we sure that amdgpu_gem_prime_pin() is only called once for each GEM object? Could in theory be that somebody exports a BO to another GFX device as well as a V4L device for example. In this case we would need a counter, but I need to double check that as well. In general I would protected the flag/counter by the BO being reserved to avoid any races. In other word move those lines a bit down after the amdgpu_bo_reserve(). Regards, Christian.
