There's only one exclusive slot, and we must not break the ordering.
A better fix would be to us a dma_fence_chain or _array like e.g. amdgpu now uses, but it probably makes sense to lift this into dma-resv.c code as a proper concept, so that drivers don't have to hack up their own solution each on their own. Hence go with the simple fix for now.
Another option is the fence import ioctl from Jason:
https://lore.kernel.org/dri-devel/20210610210925.642582-7-jason@jlekstrand.n...
Signed-off-by: Daniel Vetter daniel.vetter@intel.com Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: "Thomas Hellström" thomas.hellstrom@linux.intel.com Cc: Jason Ekstrand jason@jlekstrand.net --- drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c index 47e07179347a..9d717c8842e2 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c @@ -1775,6 +1775,7 @@ static int eb_move_to_gpu(struct i915_execbuffer *eb) struct i915_vma *vma = ev->vma; unsigned int flags = ev->flags; struct drm_i915_gem_object *obj = vma->obj; + bool async, write;
assert_vma_held(vma);
@@ -1806,7 +1807,10 @@ static int eb_move_to_gpu(struct i915_execbuffer *eb) flags &= ~EXEC_OBJECT_ASYNC; }
- if (err == 0 && !(flags & EXEC_OBJECT_ASYNC)) { + async = flags & EXEC_OBJECT_ASYNC; + write = flags & EXEC_OBJECT_WRITE; + + if (err == 0 && (!async || write)) { err = i915_request_await_object (eb->request, obj, flags & EXEC_OBJECT_WRITE); }