Am Montag, 16. November 2015, 16:52:06 schrieb Liviu Dudau:

On Mon, Nov 16, 2015 at 04:30:16PM +0000, Russell King - ARM Linux wrote:

quoted

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:

quoted

-	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':

quoted

+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!

Russell's hint was correct. With the compare function changed like he pointed 
out, I again get a working display with your patches :-)

So, thanks Russell for spotting this.


Heiko