diff --git a/sys/src/9/bcm/vcore.c b/sys/src/9/bcm/vcore.c
index 818c12a35..91cc7dcf9 100644
--- a/sys/src/9/bcm/vcore.c
+++ b/sys/src/9/bcm/vcore.c
@@ -53,6 +53,7 @@ enum {
 	TagSetEgpioConf	= 0x00038043,
 
 	TagGettemp	= 0x00030006,
+	TagXhciReset	= 0x00030058,
 	TagFballoc	= 0x00040001,
 	TagFbfree	= 0x00048001,
 	TagFbblank	= 0x00040002,
@@ -413,3 +414,19 @@ egpset(uint port, int on)
 	buf[1] = on;
 	vcreq(TagSetEgpioState, buf, sizeof(buf), sizeof(buf));
 }
+
+/*
+ * Notify gpu that xhci firmware might need loading. This is for some
+ * pi4 board versions which are missing the eeprom chip for the vl805,
+ * requiring its firmware to come from the boot eeprom instead.
+ */
+int
+xhcireset(int devaddr)
+{
+	u32int buf[1];
+
+	buf[0] = devaddr;
+	if(vcreq(TagXhciReset, buf, sizeof(buf), sizeof(buf[0])) == sizeof(buf[0]))
+		return buf[0];
+	return -1;
+}
diff --git a/sys/src/9/bcm64/archbcm4.c b/sys/src/9/bcm64/archbcm4.c
index 55e90d45a..d47ba96e1 100644
--- a/sys/src/9/bcm64/archbcm4.c
+++ b/sys/src/9/bcm64/archbcm4.c
@@ -172,5 +172,18 @@ wakecpu(uint cpu)
 void
 archbcm4link(void)
 {
+	Pcidev *p;
+
+	/*
+	 * The firmware resets PCI before starting the host OS because
+	 * without SDRAM the VL805 makes inbound requests to page-in firmware
+	 * from SDRAM. If the OS has a different PCI mapping that would all break.
+	 * There's no way to pause and move the mappings and it's not really desirable
+	 * for the firmware to dictate the PCI configuration. Consequently, the mailbox
+	 * is required so that the OS can reset the VLI after asserting PCI chip reset.
+	 */
+	if((p = pcimatch(nil, 0x1106, 0x3483)) != nil)
+		xhcireset(BUSBNO(p->tbdf)<<20 | BUSDNO(p->tbdf)<<15 | BUSFNO(p->tbdf)<<12);
+
 	// addclock0link(wdogfeed, HZ);
 }
diff --git a/sys/src/9/bcm64/fns.h b/sys/src/9/bcm64/fns.h
index 34cc0c812..f42c2736c 100644
--- a/sys/src/9/bcm64/fns.h
+++ b/sys/src/9/bcm64/fns.h
@@ -170,6 +170,7 @@ extern uint getcputemp(void);
 extern void vgpinit(void);
 extern void vgpset(uint port, int on);
 extern void egpset(uint port, int on);
+extern int xhcireset(int devaddr);
 
 /* bootargs */
 extern void bootargsinit(uintptr);
diff --git a/sys/src/9/bcm64/pi4 b/sys/src/9/bcm64/pi4
index 8d30d289d..1a3b815ff 100644
--- a/sys/src/9/bcm64/pi4
+++ b/sys/src/9/bcm64/pi4
@@ -27,11 +27,11 @@ dev
 link
 	gisb
 	pci
-	archbcm4
+	archbcm4	pci
+	usbxhci		pci archbcm4
 	ethergenet	ethermii
 	ethermedium
 	loopbackmedium
-	usbxhci		pci
 
 ip
 	tcp