[RFC PATCH v3] irqchip: Add support for Tango interrupt controller

On Wed, Jan 20, 2016 at 05:24:14PM +0100, Marc Gonzalez wrote:

On 20/01/2016 17:10, M?ns Rullg?rd wrote:

quoted

Marc Zyngier wrote:

quoted

quoted

+	if (of_property_read_u32(node, "reg", &ctl))
+		panic("%s: failed to get reg base", node->name);
+
+	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+	chip->ctl = ctl;
+	chip->base = base;

As I said before, this assumes the outer DT node uses a ranges
property.  Normally reg properties work the same whether they specify an
offset within an outer "ranges" or have a full address directly.  It
would be easy enough to make this work with either, so I don't see any
reason not to.

IIRC, I was told very early in the review process that the ranges prop
was mandatory. Lemme look for it... It was Arnd:

http://thread.gmane.org/gmane.linux.ports.arm.kernel/444131/focus=444207

I believe Arnd's point was that you need _a_ ranges property, rather
than specifically requiring an idmap/empty ranges property.

As Marc pointed out, you can use of_iomap on the child nodes to map the
portions described by the reg properties, which will handle any
ranges-based translation automatically.

When you put together the binding document, please point out that the
ranges property is necessary.

Thanks,
Mark.