linux-kernel - Re: [PATCH v4 04/11] device property: Add functions for accessing node's parents

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Date:   Mon, 2 Sep 2019 15:34:31 +0300
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Petr Mladek <pmladek@...e.com>, linux-kernel@...r.kernel.org,
        rafael@...nel.org, linux-acpi@...r.kernel.org,
        devicetree@...r.kernel.org, Rob Herring <robh@...nel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: Re: [PATCH v4 04/11] device property: Add functions for accessing
 node's parents

Hi Andy,

On Mon, Sep 02, 2019 at 01:14:26PM +0300, Andy Shevchenko wrote:
> On Mon, Sep 02, 2019 at 11:32:33AM +0300, Sakari Ailus wrote:
> > Add two convenience functions for accessing node's parents:
> > 
> > fwnode_count_parents() returns the number of parent nodes a given node
> > has. fwnode_get_nth_parent() returns node's parent at a given distance
> > from the node itself.
> > 
> 
> Much better now, thanks!
> 
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> 
> though one question below.

Thanks!

...

> > +/**
> > + * fwnode_get_nth_parent - Return an nth parent of a node
> > + * @fwnode: The node the parent of which is requested
> > + * @depth: Distance of the parent from the node
> > + *
> > + * Returns the nth parent of a node. If @depth is 0, the functionality is
> > + * equivalent to fwnode_handle_get(). For @depth == 1, it is fwnode_get_parent()
> > + * and so on.
> > + *
> > + * The caller is responsible for calling fwnode_handle_put() for the returned
> > + * node.
> > + */
> > +struct fwnode_handle *fwnode_get_nth_parent(struct fwnode_handle *fwnode,
> > +					    unsigned int depth)
> > +{
> > +	unsigned int i;
> > +
> > +	fwnode_handle_get(fwnode);
> > +
> > +	for (i = 0; i < depth && fwnode; i++)
> > +		fwnode = fwnode_get_next_parent(fwnode);
> > +
> 
> If 'fnode == NULL' and 'i < depth', shan't we return some kind of error?

How about adding to the comment, after the first sentence of the
description:

	If there is no parent at the requested depth, NULL is returned.

-- 
Sakari Ailus
sakari.ailus@...ux.intel.com