Re: [PATCH 04/12] usb: common: Small class for USB role switches

Heikki Krogerus
2018-02-16T14:22:09Z

On Fri, Feb 16, 2018 at 04:07:59PM +0200, Andy Shevchenko wrote:
> On Fri, Feb 16, 2018 at 12:47 PM, Hans de Goede <hdegoede@redhat.com> wrote:
>
> > USB role switch is a device that can be used to choose the
> > data role for USB connector. With dual-role capable USB
> > controllers, the controller itself will be the switch, but
> > on some platforms the USB host and device controllers are
> > separate IPs and there is a mux between them and the
> > connector. On those platforms the mux driver will need to
> > register the switch.
> >
> > With USB Type-C connectors, the host-to-device relationship
> > is negotiated over the Configuration Channel (CC). That
> > means the USB Type-C drivers need to be in control of the
> > role switch. The class provides a simple API for the USB
> > Type-C drivers for the control.
> >
> > For other types of USB connectors (mainly microAB) the class
> > provides user space control via sysfs attribute file that
> > can be used to request role swapping from the switch.
>
> > +static int __switch_match(struct device *dev, const void *name)
>
> bool?

No, this is callback for class_find_device(). It takes int so int it
is.

> > +{
> > + return !strcmp((const char *)name, dev_name(dev));
> > +}
>
>
> > +static ssize_t role_store(struct device *dev, struct device_attribute *attr,
> > + const char *buf, size_t size)
> > +{
> > + struct usb_role_switch *sw = to_role_switch(dev);
> > + int ret;
> > +
> > + ret = sysfs_match_string(usb_roles, buf);
> > + if (ret < 0) {
> > + bool res;
> > +
> > + /* Extra check if the user wants to disable the switch */
> > + ret = kstrtobool(buf, &res);
> > + if (ret || res)
> > + return -EINVAL;
> > + }
> > +
>
> > + ret = usb_role_switch_set_role(sw, ret);
> > + if (!ret)
> > + ret = size;
> > +
> > + return ret;
>
> Perhaps
>
> ret = ...
> if (ret)
> return ret;
>
> return size;

Sure. Hans, can you clean-up this as well?

> > +}
>
> > +struct usb_role_switch *
> > +usb_role_switch_register(struct device *parent,
> > + const struct usb_role_switch_desc *desc)
> > +{
> > + struct usb_role_switch *sw;
> > + int ret;
> > +
> > + if (!desc || !desc->set)
> > + return ERR_PTR(-EINVAL);
> > +
> > + sw = kzalloc(sizeof(*sw), GFP_KERNEL);
> > + if (!sw)
> > + return ERR_PTR(-ENOMEM);
>
> > + ret = device_register(&sw->dev);
> > + if (ret) {
> > + put_device(&sw->dev);
>
> Memory leak?

No. Check usb_role_switch_release().

Thanks,

--
heikki