drm/i915: limit the async bind to bind_async_flags

If the vm doesn't request async binding, like for example with the dpt,
then we should be able to skip the async path and avoid calling
i915_vm_lock_objects() altogether. Currently if we have a moving fence
set for the BO(even though it might have signalled), we still take the
async patch regardless of the bind_async setting, and then later still
end up just doing i915_gem_object_wait_moving_fence() anyway.

Alternatively we would need to add dummy scratch object which can be
locked, just for the dpt.

Suggested-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220304095934.925036-2-matthew.auld@intel.com

drivers/gpu/drm/i915/i915_vma.c

@@ -1370,8 +1370,7 @@ int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
 	if (flags & PIN_GLOBAL)
 		wakeref = intel_runtime_pm_get(&vma->vm->i915->runtime_pm);
 
-	moving = vma->obj ? i915_gem_object_get_moving_fence(vma->obj) : NULL;
-	if (flags & vma->vm->bind_async_flags || moving) {
+	if (flags & vma->vm->bind_async_flags) {
 		/* lock VM */
 		err = i915_vm_lock_objects(vma->vm, ww);
 		if (err)
@@ -1384,6 +1383,8 @@ int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
 		}
 
 		work->vm = vma->vm;
+
+		moving = vma->obj ? i915_gem_object_get_moving_fence(vma->obj) : NULL;
 		dma_fence_work_chain(&work->base, moving);
 
 		/* Allocate enough page directories to used PTE */