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

Hans de Goede
2018-02-19T09:32:21Z

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@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?

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,
>