From 9081d750d72b74f44e12fb2b46823378f8500217 Mon Sep 17 00:00:00 2001
From: sf <sf@openbsd.org>
Date: Tue, 20 Aug 2024 07:04:29 +0000
Subject: [PATCH] virtio_mmio: Return early if no device

If there is no device, don't write to any registers.

ok jan@
---
 sys/dev/fdt/virtio_mmio.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/sys/dev/fdt/virtio_mmio.c b/sys/dev/fdt/virtio_mmio.c
index 5c285470c1b..c88d58e3efb 100644
--- a/sys/dev/fdt/virtio_mmio.c
+++ b/sys/dev/fdt/virtio_mmio.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: virtio_mmio.c,v 1.13 2024/05/17 16:37:10 sf Exp $	*/
+/*	$OpenBSD: virtio_mmio.c,v 1.14 2024/08/20 07:04:29 sf Exp $	*/
 /*	$NetBSD: virtio.c,v 1.3 2011/11/02 23:05:52 njoly Exp $	*/
 
 /*
@@ -271,16 +271,16 @@ virtio_mmio_attach(struct device *parent, struct device *self, void *aux)
 	id = bus_space_read_4(sc->sc_iot, sc->sc_ioh, VIRTIO_MMIO_DEVICE_ID);
 	printf(": Virtio %s Device", virtio_device_string(id));
 
-	if (sc->sc_version == 1)
-		bus_space_write_4(sc->sc_iot, sc->sc_ioh,
-		    VIRTIO_MMIO_GUEST_PAGE_SIZE, PAGE_SIZE);
-
 	printf("\n");
 
 	/* No device connected. */
 	if (id == 0)
 		return;
 
+	if (sc->sc_version == 1)
+		bus_space_write_4(sc->sc_iot, sc->sc_ioh,
+		    VIRTIO_MMIO_GUEST_PAGE_SIZE, PAGE_SIZE);
+
 	vsc->sc_ops = &virtio_mmio_ops;
 	vsc->sc_dmat = sc->sc_dmat;
 	sc->sc_config_offset = VIRTIO_MMIO_CONFIG;
-- 
2.20.1