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

[Hans de Goede]

Hi,

On 16-02-18 15:22, Heikki Krogerus wrote:
> 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@xxxxxxxxxx> 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?

Yes I can, not sure when exactly I will get around to this, but I will
try to get out a v2 addressing all comments made this week.

And thank you for your reviews.

Andy, thank you for all the reviews too.

Regards,

Hans

> > > +}
> >
> > > +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,