linux-kernel - Re: [PATCH] mfd: arizona: convert to regmap_add_irq

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Date:	Mon, 30 Jul 2012 11:05:08 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
CC:	Samuel Ortiz <sameo@...ux.intel.com>, linux-kernel@...r.kernel.org,
	Stephen Warren <swarren@...dia.com>
Subject: Re: [PATCH] mfd: arizona: convert to regmap_add_irq_chips

On 07/29/2012 02:38 PM, Mark Brown wrote:
> On Fri, Jul 27, 2012 at 01:02:56PM -0600, Stephen Warren wrote:
>> From: Stephen Warren <swarren@...dia.com>
>>
>> The Arizona chip contains a single interrupt that represents the unified
>> output of multiple internal interrupt controllers. This pattern has been
>> factored out into regmap-irq, so convert the Arizona driver to use the
>> new regmap-irq code.
> 
> So, I didn't like the patch this depends on but anyway..
> 
>> 1) regmap_add_irq_chips() calls regmap_add_irq_chip() with irq==0 rather
>>    than -1, so in turn irq_domain_add_linear() is called rather than
>>    irq_domain_add_legacy(). This change could be avoided by providing an
>>    irq_bases array to regmap_add_irq_chips().
> 
> This is a problem.

OK, can you explain why? Is the problem the difference between the two
types of IRQ domain? I would have assumed this was an internal detail of
the driver hence not an issue. I assume there's no issue with
known/static IRQ numbers, since both 0 and -1 end up dynamically
allocating the IRQ bases IIRC.

>> 2) regmap_add_irq_chips() requests the top-level interrupt itself, so this
>>    happens before the Arizona driver hooks the child BOOT_DONE and
>>    CTRLIF_ERR interrupts. In the original, all the IRQ chips were created
>>    first, and then the top-level IRQ was requested. This may cause a
>>    functional difference if those interrupts are pending at probe() time.
> 
> Boot done is very likely to be asserted.

Hmmm. Perhaps that means regmap_add_irq_chips() should be split into two
parts; one to create all the IRQ chips and hook everything together, and
the second to actually enable the interrupt.
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