linux-kernel - RE: [PATCH v3 1/1] device property: Allow error pointer to be passed to fwnode APIs

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Date:   Tue, 8 Mar 2022 10:32:26 +0000
From:   "Sa, Nuno" <Nuno.Sa@...log.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>
Subject: RE: [PATCH v3 1/1] device property: Allow error pointer to be passed
 to fwnode APIs

> From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Sent: Tuesday, March 8, 2022 11:10 AM
> To: Sa, Nuno <Nuno.Sa@...log.com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>; linux-
> acpi@...r.kernel.org; linux-kernel@...r.kernel.org; Daniel Scally
> <djrscally@...il.com>; Heikki Krogerus
> <heikki.krogerus@...ux.intel.com>; Sakari Ailus
> <sakari.ailus@...ux.intel.com>; Greg Kroah-Hartman
> <gregkh@...uxfoundation.org>; Rafael J. Wysocki
> <rafael@...nel.org>; Len Brown <lenb@...nel.org>
> Subject: Re: [PATCH v3 1/1] device property: Allow error pointer to be
> passed to fwnode APIs
> 
> [External]
> 
> On Tue, Mar 08, 2022 at 09:25:07AM +0000, Sa, Nuno wrote:
> > > -----Original Message-----
> > > From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > > Sent: Monday, March 7, 2022 9:30 PM
> 
> ...
> 
> > > v3: dropped test of secondary fwnode (Nuno), added tag (Nuno),
> > > amended commit message
> > > v2: adjusted the entire fwnode API (Sakari)
> > >
> > > Nuno, can you re-test this with the ltc2983 series to be sure it is still
> > > okay?
> >
> > Still works!
> 
> Thanks for confirming!
> 
> ...
> 
> > > @@ -988,14 +998,14 @@
> fwnode_graph_get_next_endpoint(const
> > > struct fwnode_handle *fwnode,
> > >  		parent = fwnode_graph_get_port_parent(prev);
> > >  	else
> > >  		parent = fwnode;
> > > +	if (IS_ERR_OR_NULL(parent))
> > > +		return NULL;
> 
> (1)
> 
> > >  	ep = fwnode_call_ptr_op(parent, graph_get_next_endpoint,
> > > prev);
> > > +	if (ep)
> > > +		return ep;
> >
> > I might be missing something but before the check being done was
> > 'if (IS_ERR_OR_NULL(ep)'. Is there anyway for ep to be an error
> > pointer? Looking at OF, It seems that only NULL or a valid pointer
> > is being returned. Did not looked at others implementations of
> > though...
> 
> Yes, the IS_ERR() part is redundant there. I was quite confused with
> that code while working on this change. So, now it looks much clearer
> what's going on and what kind of values are being expected. This also
> justifies the choice of returned value in (1).
> 

Makes sense to me.

Acked-by: Nuno Sá <nuno.sa@...log.com>

> --
> With Best Regards,
> Andy Shevchenko
>