remoteproc: don't use virtio's weak barriers

When creating a virtqueue for rpmsg, tell virtio we're not interested
in "weak" smp barriers, since we're talking to a real device.

On ARM, this means using a DSB instead of a DMB, which is needed
for platforms that kick the remote processor using some kind of
a mailbox device mapped to Device memory (otherwise the kick can
jump ahead and wake the remote processor before it has observed
the changes to the vrings).

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>

drivers/remoteproc/remoteproc_rpmsg.c

@@ -96,7 +96,11 @@ static struct virtqueue *rp_find_vq(struct virtio_device *vdev,
 
 	dev_dbg(rproc->dev, "vring%d: va %p qsz %d\n", id, addr, len);
 
-	vq = vring_new_virtqueue(len, AMP_VRING_ALIGN, vdev, addr,
+	/*
+	 * Create the new vq, and tell virtio we're not interested in
+	 * the 'weak' smp barriers, since we're talking with a real device.
+	 */
+	vq = vring_new_virtqueue(len, AMP_VRING_ALIGN, vdev, false, addr,
 					rproc_virtio_notify, callback, name);
 	if (!vq) {
 		dev_err(rproc->dev, "vring_new_virtqueue %s failed\n", name);