Re: [PATCH v1 3/3] ARM64 LPC: update binding doc

From: Rongrong Zou
Date: Wed Jan 13 2016 - 06:06:57 EST

On 2016/1/13 18:09, liviu.dudau@xxxxxxx wrote:
On Tue, Jan 12, 2016 at 11:54:59PM +0100, Arnd Bergmann wrote:
On Tuesday 12 January 2016 10:14:18 liviu.dudau@xxxxxxx wrote:

OK, looking at of_translate_one() comments it looks like a missing "ranges" property is
only accepted on PowerPC. I suggest you have an empty "ranges" property in your isa
parent node, that will signal to the OF parsing code that the mapping is 1:1. Then have
the IPMI node use the reg = <0x0 0xe4 4>; property values instead of reg = <0x1 0xe4 4>;

A missing ranges property means that there is no translation, while an
empty ranges means a 1:1 translation to the parent bus.

We really want the former here, as I/O port addresses are not mapped into
the MMIO space of the parent bus.

Agree. However of_translate_one()'s behaviour doesn't match our expectations and I have no
useful suggestions on what the right behaviour should be.

I had tried to modify the drivers/of/address.c to address this problem, but it looks
not so general. I'm not sure you have seen this: .