linux-kernel - Re: [RFC PATCH v3] irqchip: Add support for Tango interrupt controller

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Message-ID: <yw1xfuxpmv2f.fsf@unicorn.mansr.com>
Date:	Fri, 22 Jan 2016 16:35:04 +0000
From:	Måns Rullgård <mans@...sr.com>
To:	Marc Gonzalez <marc_gonzalez@...madesigns.com>
Cc:	Marc Zyngier <marc.zyngier@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux ARM <linux-arm-kernel@...ts.infradead.org>,
	Sebastian Frias <sf84@...oste.net>
Subject: Re: [RFC PATCH v3] irqchip: Add support for Tango interrupt controller

Marc Gonzalez <marc_gonzalez@...madesigns.com> writes:

> On 20/01/2016 19:09, Måns Rullgård wrote:
>
>> Marc Gonzalez <marc_gonzalez@...madesigns.com> writes:
>> 
>>> On 20/01/2016 17:38, Måns Rullgård wrote:
>>>
>>>> Marc Gonzalez <marc_gonzalez@...madesigns.com> writes:
>>>>
>>>>> On 20/01/2016 17:25, Måns Rullgård wrote:
>>>>>
>>>>>> Marc Zyngier <marc.zyngier@....com> writes:
>>>>>>
>>>>>>> On 20/01/16 16:10, Måns Rullgård wrote:
>>>>>>>
>>>>>>>> Marc Zyngier <marc.zyngier@....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."
>>>>
>>>> That's going to get very messy since the generic irqchip code needs all
>>>> the registers as offsets from a common base address.
>>>
>>> The two suggestions are over my head at the moment.
>>>
>>> Do you want to submit v4 and have Marc Z take a look?
>> 
>> Done.  If this isn't acceptable either, I'm out of ideas that don't end
>> up being far uglier than anything suggested so far.
>
> With your latest patch, can I drop the ranges property?

Why would you want to do that?

-- 
Måns Rullgård