Re: usb: gadget breakage on N900: bind UDC by name passed via usb_gadget_driver structure

Pavel Machek
2016-03-23T12:21:52Z

On Mon 2016-03-21 12:51:51, Marek Szyprowski wrote:
> Hi
>
> On 2016-03-18 21:20, Pavel Machek wrote:
> >Hi!
> >
> >>>USB gadget stops working for me on n900, if I merge
> >>Could you please give us more details?
> >>Which gadget driver do you use (g_nokia?)
> >Ok, so I could get it to work with v4.5, and this patch. I'm including
> >my config, too. No, I don't think I'm using g_nokia.
>
> This shows that there are some serious problems, probably with your udc
> driver, which doesn't handle deferred probe properly. Your patch workaround
> it by waiting some predefined time before registering gadget driver, however
> this is not the proper way. Please try to isolate what exactly is needed to
> get the gadget driver registered properly in your system or at least please
> provide some logs from the failed case.

Well, Ruslan said he has n900 available, so I provided requested
information.

This is the dmesg with the hack:

[ 0.623138] of_get_named_gpiod_flags: parsed 'ti,power-gpio'
property of node '/ocp/spi@480ba00
0/wl1251@0[0]' - status (0)
[ 0.623565] wl1251: ERROR vio regulator missing: -517
[ 0.624359] musb probe HACK cf9a9e00
[ 0.624420] musb probe HACK/2 cf9a9e00
[ 0.624511] musb probe HACK/3 cf9a9e00
[ 0.624755] HS USB OTG: no transceiver configured
[ 0.624847] musb-hdrc musb-hdrc.0.auto: musb_init_controller failed
with status -517
[ 0.626525] mousedev: PS/2 mouse device common for all mice
...
[ 2.877441] ieee80211 phy1: Selected rate control algorithm
'minstrel'
[ 2.879882] wl1251: loaded
[ 2.889617] wl1251: initialized
[ 2.897521] Two musb controllers? HACK
[ 2.904968] musb probe HACK cf9a9e00
[ 2.912048] musb probe HACK/2 cf9a9e00
[ 2.918823] musb probe HACK/3 cf9a9e00
[ 2.928985] musb-hdrc: ConfigData=0xde (UTMI-8, dyn FIFOs, bulk
combine, bulk split, HB-ISO Rx, HB-ISO Tx, SoftConn)
[ 2.929016] musb-hdrc: MHDRC RTL version 1.400
[ 2.929046] musb-hdrc: setup fifo_mode 4
[ 2.929077] musb-hdrc: 28/31 max ep, 16384/16384 memory
[ 2.930511] tsc2005 spi1.0: GPIO lookup for consumer reset
[ 2.930541] tsc2005 spi1.0: using device tree for GPIO lookup

In the kernel without the hack, there'll be only the first part of the
dmesg, AFAICT.

If there's an interest, I can repeat the test without the hack.

Thanks,
Pavel

> >diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
> >index b86a6f0..bee109f 100644
> >--- a/drivers/usb/gadget/udc/udc-core.c
> >+++ b/drivers/usb/gadget/udc/udc-core.c
> >@@ -542,14 +542,37 @@ err1:
> > return ret;
> > }
> >-int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
> >+int usb_udc_attach_driver(const char *name, struct usb_gadget_driver *driver)
> >+{
> >+ struct usb_udc *udc = NULL;
> >+ int ret = -ENODEV;
> >+
> >+ mutex_lock(&udc_lock);
> >+ list_for_each_entry(udc, &udc_list, list) {
> >+ ret = strcmp(name, dev_name(&udc->dev));
> >+ if (!ret)
> >+ break;
> >+ }
> >+ if (ret) {
> >+ ret = -ENODEV;
> >+ goto out;
> >+ }
> >+ if (udc->driver) {
> >+ ret = -EBUSY;
> >+ goto out;
> >+ }
> >+ ret = udc_bind_to_driver(udc, driver);
> >+out:
> >+ mutex_unlock(&udc_lock);
> >+ return ret;
> >+}
> >+EXPORT_SYMBOL_GPL(usb_udc_attach_driver);
> >+
> >+int __usb_gadget_probe_driver(struct usb_gadget_driver *driver)
> > {
> > struct usb_udc *udc = NULL;
> > int ret = -ENODEV;
> >- if (!driver || !driver->bind || !driver->setup)
> >- return -EINVAL;
> >-
> > mutex_lock(&udc_lock);
> > if (driver->udc_name) {
> > list_for_each_entry(udc, &udc_list, list) {
> >@@ -567,16 +590,47 @@ int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
> > }
> > }
> >- list_add_tail(&driver->pending, &gadget_driver_pending_list);
> >+// list_add_tail(&driver->pending, &gadget_driver_pending_list); FIXME
> > pr_info("udc-core: couldn't find an available UDC - added [%s] to list of pending drivers\n",
> > driver->function);
> >+
> > mutex_unlock(&udc_lock);
> >- return 0;
> >+ return ret;
> > found:
> > ret = udc_bind_to_driver(udc, driver);
> > mutex_unlock(&udc_lock);
> > return ret;
> > }
> >+
> >+#define USB_GADGET_BIND_RETRIES 5
> >+#define USB_GADGET_BIND_TIMEOUT (3 * HZ)
> >+static void usb_gadget_work(struct work_struct *work)
> >+{
> >+ struct usb_gadget_driver *driver = container_of(work,
> >+ struct usb_gadget_driver,
> >+ work.work);
> >+ int res;
> >+
> >+ if (driver->retries++ > USB_GADGET_BIND_RETRIES) {
> >+ pr_err("couldn't find an available UDC\n");
> >+ return;
> >+ }
> >+
> >+ res = __usb_gadget_probe_driver(driver);
> >+ if (res == -ENODEV)
> >+ schedule_delayed_work(&driver->work, USB_GADGET_BIND_TIMEOUT);
> >+}
> >+
> >+int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
> >+{
> >+ if (!driver || !driver->bind || !driver->setup)
> >+ return -EINVAL;
> >+
> >+ INIT_DELAYED_WORK(&driver->work, usb_gadget_work);
> >+ schedule_delayed_work(&driver->work, 0);
> >+
> >+ return 0;
> >+}
> > EXPORT_SYMBOL_GPL(usb_gadget_probe_driver);
> > int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
> >@@ -587,6 +641,8 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
> > if (!driver || !driver->unbind)
> > return -EINVAL;
> >+ cancel_delayed_work(&driver->work);
> >+
> > mutex_lock(&udc_lock);
> > list_for_each_entry(udc, &udc_list, list)
> > if (udc->driver == driver) {
> >@@ -747,7 +803,7 @@ static int __init usb_udc_init(void)
> > udc_class->dev_uevent = usb_udc_uevent;
> > return 0;
> > }
> >-subsys_initcall(usb_udc_init);
> >+late_initcall_sync(usb_udc_init);
> > static void __exit usb_udc_exit(void)
> > {
> >diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
> >index d82d006..adb1e68 100644
> >--- a/include/linux/usb/gadget.h
> >+++ b/include/linux/usb/gadget.h
> >@@ -1014,6 +1014,8 @@ static inline int usb_gadget_activate(struct usb_gadget *gadget)
> > * @resume: Invoked on USB resume. May be called in_interrupt.
> > * @reset: Invoked on USB bus reset. It is mandatory for all gadget drivers
> > * and should be called in_interrupt.
> >+ * @work: Gadget work used to bind to the USB controller.
> >+ * @retries: Gadget retries to bind to the USB controller.
> > * @driver: Driver model state for this driver.
> > * @udc_name: A name of UDC this driver should be bound to. If udc_name is NULL,
> > * this driver will be bound to any available UDC.
> >@@ -1075,6 +1077,8 @@ struct usb_gadget_driver {
> > void (*suspend)(struct usb_gadget *);
> > void (*resume)(struct usb_gadget *);
> > void (*reset)(struct usb_gadget *);
> >+ struct delayed_work work;
> >+ int retries;
> > /* FIXME support safe rmmod */
> > struct device_driver driver;
> >
>
> Best regards