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Subject: Re: [RFC PATCH v3] irqchip: Add support for Tango interrupt
 controller
To: Mans Rullgard <mans@mansr.com>, Marc Zyngier <marc.zyngier@arm.com>
CC: Thomas Gleixner <tglx@linutronix.de>, Jason Cooper <jason@lakedaemon.net>,
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        Sebastian Frias <sf84@laposte.net>
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From: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
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Date: Wed, 20 Jan 2016 17:36:57 +0100
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On 20/01/2016 17:25, Måns Rullgård wrote:

> Marc Zyngier <marc.zyngier@arm.com> writes:
> 
>> On 20/01/16 16:10, Måns Rullgård wrote:
>>
>>> Marc Zyngier <marc.zyngier@arm.com> writes:
>>>
>>>>> +	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.
>>
>> Yup, that is a good point. I guess Marc can address this in the next
>> round, since we need a DT binding anyway.
> 
> I'd suggest using of_address_to_resource() on both nodes and subtracting
> the start addresses returned.

For my own reference, Marc Zyngier suggested:
"you should use of_iomap to map the child nodes, and not mess with
the parent one."