linux-kernel - Re: [PATCH v5 4/6] usb: roles: add API to get usb_role

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Date:   Mon, 27 May 2019 13:45:06 +0300
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>
Cc:     Biju Das <biju.das@...renesas.com>,
        Rob Herring <robh+dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Adam Thomson <Adam.Thomson.Opensource@...semi.com>,
        Li Jun <jun.li@....com>,
        Badhri Jagan Sridharan <badhri@...gle.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Min Guo <min.guo@...iatek.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v5 4/6] usb: roles: add API to get usb_role_switch by node

Hi,

> > IMO that case should be handled in USB role switch API initially, not
> > in the device connection API. If there is another user for it one day,
> > then we can move it to device connection API, but not before that.
> Ok
> > 
> > How about this on top of the two patches I sent:
> I just test it, it works well.
> I'll prepare a patch and put into this series.
> 
> > 
> > diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
> > index aab795b54c7f..36ac9d181e09 100644
> > --- a/drivers/usb/roles/class.c
> > +++ b/drivers/usb/roles/class.c
> > @@ -114,6 +114,19 @@ static void *usb_role_switch_match(struct device_connection *con, int ep,
> >         return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
> >  }
> > 
> > +static struct usb_role_switch *
> > +usb_role_switch_is_parent(struct fwnode_handle *parent)
> > +{
> > +       struct device *dev;
> > +
> > +       if (!parent || !fwnode_property_present(parent, "usb-role-switch"))
> > +               return NULL;
> > +
> > +       dev = class_find_device(role_class, NULL, parent, switch_fwnode_match);
> > +
> > +       return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
> > +}
> > +
> >  /**
> >   * usb_role_switch_get - Find USB role switch linked with the caller
> >   * @dev: The caller device
> > @@ -125,6 +138,10 @@ struct usb_role_switch *usb_role_switch_get(struct device *dev)
> >  {
> >         struct usb_role_switch *sw;
> > 
> > +       sw = usb_role_switch_is_parent(fwnode_get_parent(dev_fwnode(dev)));
> > +       if (sw)
> > +               return sw;
> Do we also need to get parent module before return?

Yes.

thanks,

-- 
heikki