Hello Felipe,
I am not an expert on Linux Kernel but I have a problem with the USB
gadget and the origin seems to be there.
I am working with Kernel 4.13.0 on Stamp 9G20 from Taskit GmbH (CPU:
Atmel AT91SAM9G20 Embedded Processor featuring an ARM926EJ-STM ARM®
Thumb® Core).
The problem is, the disconnection of the USB gadget cable is not
acquainted by the Kernel. There is nothing in dmesg.
When I connect the cable, there is a reaction visible in dmesg:
[ 1711.406250] g_ether gadget: full-speed config #1: CDC Ethernet (ECM)
[ 1711.414062] IPv6: ADDRCONF(NETDEV_CHANGE): usb0: link becomes ready
Kernel modules loaded:
Module Size Used by
usb_f_ecm 9123 1
g_ether 4488 0
usb_f_rndis 20935 2 g_ether
u_ether 10799 3 usb_f_ecm,g_ether,usb_f_rndis
libcomposite 44168 3 usb_f_ecm,g_ether,usb_f_rndis
After disconnecting the cable, usb0 is still shown as connected:
4: usb0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
state UP group default qlen 1000
link/ether 8e:8e:76:28:44:ab brd ff:ff:ff:ff:ff:ff
inet 169.254.169.4/16 brd 169.254.255.255 scope link usb0
valid_lft forever preferred_lft forever
inet6 fe80::8c8e:76ff:fe28:44ab/64 scope link
valid_lft forever preferred_lft forever
We used to work with an older Kernel (3.2) and we had a patch for this
problem. We expected it to be solved in 4.13 but it isn't.
diff --git a/drivers/usb/gadget/at91_udc.c b/drivers/usb/gadget/at91_udc.c
index 8efe0fa..423fc6a 100644
--- a/drivers/usb/gadget/at91_udc.c
+++ b/drivers/usb/gadget/at91_udc.c
@@ -1395,6 +1395,7 @@ static irqreturn_t at91_udc_irq (int irq, void *_udc)
u32 rescans = 5;
int disable_clock = 0;
unsigned long flags;
+ struct usb_ctrlrequest req;
spin_lock_irqsave(&udc->lock, flags);
@@ -1443,7 +1444,18 @@ static irqreturn_t at91_udc_irq (int irq, void *_udc)
at91_udp_write(udc, AT91_UDP_ICR, AT91_UDP_RXSUSP);
/* VDBG("bus suspend\n"); */
if (udc->suspended)
- continue;
+ continue;
+
+ /* tell the driver the disconnect */
+ if (udc->driver) {
+ spin_unlock(&udc->lock);
+ memset(&req, 0, sizeof(req));
+ req.bRequestType = USB_DIR_OUT | USB_TYPE_STANDARD |
USB_RECIP_DEVICE;
+ req.bRequest = USB_REQ_SET_CONFIGURATION;
+ status = udc->driver->setup(&udc->gadget, &req);
+ spin_lock(&udc->lock);
+ }
+
udc->suspended = 1;
/*
Please let me know if I can supply more information or if I should
address another maintainer.
Thanks
Ana
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