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SubjectRe: [PATCH 2/2] drm/rockchip: Convert the probe function to the generic drm_of_component_probe()
On Mon, Nov 16, 2015 at 04:30:16PM +0000, Russell King - ARM Linux wrote:
> I've tweaked your patch to make the above (buggy) change a little clearer.
>
> On Mon, Nov 16, 2015 at 02:44:53PM +0000, Liviu Dudau wrote:
> > - for (i = 0;; i++) {
> > - port = of_parse_phandle(np, "ports", i);
> > - if (!port)
> > - break;
> > -
> > - if (!of_device_is_available(port->parent)) {
> > - of_node_put(port);
> > - continue;
> > - }
> >
> > - component_match_add(dev, &match, compare_of, port->parent);
> > - of_node_put(port);
> > - }
>
> > -static int compare_of(struct device *dev, void *data)
> > -{
> > - struct device_node *np = data;
> > -
> > - return dev->of_node == np;
> > -}
>
> The original above passes port->parent to component_match_add(). This
> means 'np' in the above compare_of() function is 'port->parent'.
>
> This means the above comparison is effectively:
>
> dev->of_node == port->parent
>
> The generic code instead does this:
>
> component_match_add(dev, &match, compare_of, port);
>
> So what we get in the comparison function is 'port' rather than
> 'port->parent':
>
> > +static int compare_port(struct device *dev, void *data)
> > {
> > + struct device_node *np = data;
> > + return dev->parent->of_node == np;
> > +}
>
> which means the comparison is:
>
> dev->parent->of_node == port
>
> which is a different comparison from the above.
>
> You instead want this to be:
>
> return dev->of_node == np->parent;
>
> Heiko, please test the above change to compare_port() - I think you'll
> find that will fix your issue.

Sorry, I admit I'm not very good at doing patches without being able
to test them. :(

Thanks for helping on this!

Liviu

>
> Thanks.
>
> --
> FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
> according to speedtest.net.
>

--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯


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