Configuring host_addr and device_addr for u_ether

[Felipe Balbi <felipe.balbi@linux.intel.com>]

Hi,

(please break your lines at 80-columns)

"Westermann, Oliver" <Oliver.Westermann@cognex.com> writes:
> Hey,
>
> I'm trying to use a composite gadget on a embedded linux platform
> using configfs. The kernel-doc was fine and I can now create my
> gadgets as needed. One big drawback is that the host_addr and dev_addr
> change on every start.
>
> So I tried to change them, without success:
>
> * Most web documentation applies only to g_ether (eg setting
> module/kernel parameters)
>
> * ${CONFIGFS}/usb_gadget/g1/functions/rndis.0/host_addr reports EBUSY
> if I try to write it

because the gadget is already configured.

> * I checked the sources of my kernel (4.19) and the current ones to
> check if I can somehow add a MAC to the dtb of my system: It seems
> that there is no such binding.

you can write host_addr and dev_addr via configufs, but according to
code, you have to do it before adding the functions to the gadget. This,
to me, seems a bit odd. Does this patch help the situation in any way?

diff --git a/drivers/usb/gadget/function/f_ecm.c b/drivers/usb/gadget/function/f_ecm.c
index 6ce044008cf6..31279aaf3f3b 100644
--- a/drivers/usb/gadget/function/f_ecm.c
+++ b/drivers/usb/gadget/function/f_ecm.c
@@ -530,14 +530,19 @@ static int ecm_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
 static int ecm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 {
 	struct f_ecm		*ecm = func_to_ecm(f);
+	struct f_ecm_opts	*ecm_opts;
 	struct usb_composite_dev *cdev = f->config->cdev;
 
+	ecm_opts = container_of(f->fi, struct f_ecm_opts, func_inst);
+
 	/* Control interface has only altsetting 0 */
 	if (intf == ecm->ctrl_id) {
 		if (alt != 0)
 			goto fail;
 
 		VDBG(cdev, "reset ecm control %d\n", intf);
+
+		ecm_opts->running = false;
 		usb_ep_disable(ecm->notify);
 		if (!(ecm->notify->desc)) {
 			VDBG(cdev, "init ecm ctrl %d\n", intf);
@@ -545,6 +550,7 @@ static int ecm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 				goto fail;
 		}
 		usb_ep_enable(ecm->notify);
+		ecm_opts->running = true;
 
 	/* Data interface has two altsettings, 0 and 1 */
 	} else if (intf == ecm->data_id) {
@@ -553,6 +559,7 @@ static int ecm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 
 		if (ecm->port.in_ep->enabled) {
 			DBG(cdev, "reset ecm\n");
+			ecm_opts->running = false;
 			gether_disconnect(&ecm->port);
 		}
 
@@ -585,6 +592,7 @@ static int ecm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 			net = gether_connect(&ecm->port);
 			if (IS_ERR(net))
 				return PTR_ERR(net);
+			ecm_opts->running = true;
 		}
 
 		/* NOTE this can be a minor disagreement with the ECM spec,
diff --git a/drivers/usb/gadget/function/u_ecm.h b/drivers/usb/gadget/function/u_ecm.h
index 050aa672ee7f..752258dd1c3e 100644
--- a/drivers/usb/gadget/function/u_ecm.h
+++ b/drivers/usb/gadget/function/u_ecm.h
@@ -19,6 +19,7 @@ struct f_ecm_opts {
 	struct usb_function_instance	func_inst;
 	struct net_device		*net;
 	bool				bound;
+	bool				running;
 
 	/*
 	 * Read/write access to configfs attributes is handled by configfs.
diff --git a/drivers/usb/gadget/function/u_ether_configfs.h b/drivers/usb/gadget/function/u_ether_configfs.h
index cd33cee4d78b..7fe0a7fa4e7a 100644
--- a/drivers/usb/gadget/function/u_ether_configfs.h
+++ b/drivers/usb/gadget/function/u_ether_configfs.h
@@ -46,7 +46,7 @@
 		int ret;						\
 									\
 		mutex_lock(&opts->lock);				\
-		if (opts->refcnt) {					\
+		if (opts->running) {					\
 			mutex_unlock(&opts->lock);			\
 			return -EBUSY;					\
 		}							\
@@ -81,7 +81,7 @@
 		int ret;						\
 									\
 		mutex_lock(&opts->lock);				\
-		if (opts->refcnt) {					\
+		if (opts->running) {					\
 			mutex_unlock(&opts->lock);			\
 			return -EBUSY;					\
 		}							\