linux-kernel - RE: [PATCH v2 6/9] usb: roles: Find the muxes by also matching against the device node

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Date:   Tue, 12 Feb 2019 06:03:42 +0000
From:   Jun Li <jun.li@....com>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Chen Yu <chenyu56@...wei.com>,
        Hans de Goede <hdegoede@...hat.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 6/9] usb: roles: Find the muxes by also matching
 against the device node



> -----Original Message-----
> From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> Sent: 2019年2月11日 18:46
> To: Jun Li <jun.li@....com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>; Andy Shevchenko
> <andy.shevchenko@...il.com>; Chen Yu <chenyu56@...wei.com>; Hans de
> Goede <hdegoede@...hat.com>; linux-usb@...r.kernel.org;
> linux-kernel@...r.kernel.org
> Subject: Re: [PATCH v2 6/9] usb: roles: Find the muxes by also matching against the
> device node
> 
> On Mon, Feb 11, 2019 at 09:58:04AM +0000, Jun Li wrote:
> > Hi Heikki,
> >
> > > @@ -84,7 +85,12 @@ enum usb_role usb_role_switch_get_role(struct
> > > usb_role_switch *sw)  }
> > > EXPORT_SYMBOL_GPL(usb_role_switch_get_role);
> > >
> > > -static int __switch_match(struct device *dev, const void *name)
> > > +static int switch_fwnode_match(struct device *dev, const void
> > > +*fwnode) {
> > > +	return dev_fwnode(dev) == fwnode;
> >
> > You missed the comment
> > https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flkm
> >
> l.org%2Flkml%2F2019%2F1%2F22%2F437&amp;data=02%7C01%7Cjun.li%40nx
> p.com
> > %7C8c2d40d5e5d246da34ad08d6900e31cf%7C686ea1d3bc2b4c6fa92cd99c5
> c301635
> > %7C0%7C0%7C636854788040965224&amp;sdata=db4gvXKc9InWiltsweetxXYr
> tPbtfX
> > jshPh%2FnvA24ig%3D&amp;reserved=0
> >
> > return dev_fwnode(dev->parent) == fwnode;
> 
> That's actually not the case. struct usb_role_switch_desc has a member for fwnode,
> and that's what we use with the actual mux device. Check
> usb_role_switch_register():
> 
>         ...
>         sw->dev.fwnode = desc->fwnode;
>         ...
> 
> Sorry for not realizing it before.

So desc->fwnode should be initialized before do usb_role_switch_register()?
But seems usb_role_switch_desc is a read-only object so can't be set at runtime.

usb_controller_node {
	...
	usb-role-switch;

	port {
		sw_provider_node: endpoint {
			remote-endpoint = <&sw_consumer_node>;
		};
	};
};

typec_node {
	...
	port {
		sw_consumer_node: endpoint {
			remote-endpoint = <&sw_provider_node>;
		};
	};
};

Is my understanding correct?

Thanks
Jun
> 
> 
> thanks,
> 
> --
> heikki