Re: PR 60404: Beaglebone Black: nonfunctional usb wifi

[Brook Milligan <brook%biology.nmsu.edu@localhost>]

With the help of yurix@, riastradh@, and rjs@ (thanks!), I have a
working fix for the ti_motg driver (see below).  With this applied,
the BBB will detect USB devices, including both mass storage and wifi.
However, while a mass storage device seems to work fine, wifi devices
do not.

I would greatly appreciate feedback before I commit this patch.
Although all input is welcome, there are several questions I would
appreciate answers for.

First, this code gathers all information dynamically from the device
tree, whereas there are hard-coded constants in, for example,
ti_otgreg.h; for example, the number of supported USB devices can be
determined dynamically or statically.  What is the wisdom of one
approach over the other?

Second, this patch was motivated by the problem outlined in PR 60404.
However, that problem (nonfunctional wifi) turns out to be more
complex and the solution will involve multiple steps.  This patch
addresses the first (USB device detection), but the wifi drivers still
do not work correctly (e.g., panics are triggered, cannot load
firmware errors, wpa_supplicant triggers errors, etc.).  Most of the
information currently in PR 60404 turns out to relate only to this
first USB device detection problem.  When this patch is committed,
should PR 60404 be closed and a new one opened to focus on the new
problems, or should it remain open, perhaps with additional
information?

Thanks a lot for your help.  I look forward to feedback.

Cheers,
Brook


Index: ti_motg.c
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/ti/ti_motg.c,v
retrieving revision 1.5
diff -u -r1.5 ti_motg.c
--- ti_motg.c	2 Feb 2024 22:14:04 -0000	1.5
+++ ti_motg.c	12 Jul 2026 16:44:11 -0000
@@ -49,6 +49,8 @@
 
 #include <dev/fdt/fdtvar.h>
 
+#include <libfdt.h>
+
 #ifdef USB_DEBUG
 #ifndef MOTG_DEBUG
 #define motgdebug 0
@@ -165,6 +167,47 @@
 
 	aprint_normal_dev(self, "interrupting on %s\n", intrstr);
 
+	bus_addr_t phy_ctrl_addr;
+	bus_size_t phy_ctrl_size;
+	int phy_phandle = fdtbus_get_phandle(phandle, "phys");
+	int cm_phandle = fdtbus_get_phandle(phy_phandle, "ti,ctrl_mod");
+	fdtbus_get_reg_byname(cm_phandle, "phy_ctrl", &phy_ctrl_addr, &phy_ctrl_size);
+
+#define USB_ALIAS "usb"
+#define USB_ALIAS_SIZE 16
+
+	char usb_alias[USB_ALIAS_SIZE] = USB_ALIAS;
+	int usb_ctrl_offset = 0;
+	int n = 0;
+	const char * prop = 0;
+	do {
+		if ((n = snprintf(&usb_alias[sizeof(USB_ALIAS)-1],
+				  USB_ALIAS_SIZE-(sizeof(USB_ALIAS)-1),
+				  "%d", usb_ctrl_offset)) > 0
+		    && (prop = fdt_get_alias(fdtbus_get_data(), usb_alias)) != NULL) {
+			if (OF_finddevice(prop) == phandle) {
+				break;
+			}
+		++usb_ctrl_offset;
+		}
+	} while (n > 0 && prop);
+	if (n <= 0 || !prop) {
+		aprint_error_dev(self, "cannot identify usb instance\n");
+		return;
+	}
+	usb_ctrl_offset *= CM_USBCTL_SIZE;
+ 
+	bus_space_handle_t handle;
+	if (bus_space_map(faa->faa_bst, phy_ctrl_addr, phy_ctrl_size, 0, &handle) != 0) {
+		aprint_error_dev(self, "couldn't map  control module USB registers\n");
+		return;
+	}
+
+	uint32_t usb_ctrl = bus_space_read_4(faa->faa_bst, handle, usb_ctrl_offset);
+	usb_ctrl &= ~(CM_USBCTRL_CM_PWRDN | CM_USBCTRL_OTG_PWRDN);
+	usb_ctrl |= (CM_USBCTRL_OTGVDET_EN | CM_USBCTRL_OTGSESSENDEN);
+	bus_space_write_4(faa->faa_bst, handle, usb_ctrl_offset, usb_ctrl);
+
 	sc->sc_motg.sc_iot = faa->faa_bst;
 	if (bus_space_map(sc->sc_motg.sc_iot, addr[0], size[0], 0,
 	    &sc->sc_motg.sc_ioh) != 0) {
Index: ti_otgreg.h
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/ti/ti_otgreg.h,v
retrieving revision 1.1
diff -u -r1.1 ti_otgreg.h
--- ti_otgreg.h	27 Oct 2019 16:31:26 -0000	1.1
+++ ti_otgreg.h	12 Jul 2026 16:44:11 -0000
@@ -72,3 +72,10 @@
 
 #define USB_CORE_OFFSET		0x400
 #define USB_CORE_SIZE		0x400
+
+/* Control module register: usb_ctlN */
+#define CM_USBCTL_SIZE			8
+#define CM_USBCTRL_CM_PWRDN		(1 << 0)
+#define CM_USBCTRL_OTG_PWRDN		(1 << 1)
+#define CM_USBCTRL_OTGVDET_EN		(1 << 19)
+#define CM_USBCTRL_OTGSESSENDEN		(1 << 20)