Re: [PATCH v1 07/12] usb: roles: Find the usb role switch by also matching against the device node

From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: chenyu56@huawei.com, USB <linux-usb@vger.kernel.org>,
	devicetree <devicetree@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Suzhuangluan <suzhuangluan@hisilicon.com>,
	Kongfei <kongfei@hisilicon.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Hans de Goede <hdegoede@redhat.com>,
	John Stultz <john.stultz@linaro.org>
Subject: Re: [PATCH v1 07/12] usb: roles: Find the usb role switch by also matching against the device node
Date: Mon, 3 Dec 2018 14:25:34 +0200	[thread overview]
Message-ID: <20181203122534.GD24338@kuha.fi.intel.com> (raw)
In-Reply-To: <CAHp75VfUKAQ+Q0cQz-4-=i2JL9uACBX1bVvCeNjZLL1HStDGKQ@mail.gmail.com>

Hi,

On Mon, Dec 03, 2018 at 10:17:20AM +0200, Andy Shevchenko wrote:
> On Mon, Dec 3, 2018 at 5:45 AM Yu Chen <chenyu56@huawei.com> wrote:
> >
> > This patch adds code for supporting find usb role switch by matching against
> > the device node described using of_graph.
> 
> >  #include <linux/module.h>
> >  #include <linux/mutex.h>
> >  #include <linux/slab.h>
> > +#include <linux/of.h>
> > +#include <linux/of_graph.h>
> 
> Keep it ordered.
> 
> > +static int __switch_match_by_of_node(struct device *dev, const void *name)
> > +{
> > +       if (!dev->parent || !dev->parent->of_node)
> > +               return 0;
> > +
> > +       return of_node_name_eq(dev->parent->of_node, (const char *)name);
> > +}
> 
> I think Heikki has introduced some more generic function for this.

Yes, for this I'm proposing a new function fwnode_get_name() that
should allow us to support ACPI as well as OF platforms:
https://lkml.org/lkml/2018/11/28/784

> >         sw = device_connection_find_match(dev, "usb-role-switch", NULL,
> >                                           usb_role_switch_match);
> 
> > +       sw = of_graph_find_match_by_type(dev, "usb-role-switch");
> 
> Why this is here?! device_connection_find_match() should take care for OF case.

Exactly. device_connection_find_match() needs to parse the graph (OF
and ACPI), and I already made proposal (RFC) for that:
https://lkml.org/lkml/2018/10/24/619

I have prepared a more finalized version of those patches. I've been
waiting for that fwnode_get_name() to be accepted before sending it
out since we are going to need that function, but I'll send a new RFC
if nothing happens soon with that fwnode_get_name() series.

Br,

-- 
heikki