linux-kernel - Re: [PATCH 3/3] regmap: enhance regmap-irq to handle 1 IRQ feeding n chips

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Date:	Mon, 30 Jul 2012 11:00:04 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
CC:	Liam Girdwood <lrg@...com>, linux-kernel@...r.kernel.org,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Stephen Warren <swarren@...dia.com>
Subject: Re: [PATCH 3/3] regmap: enhance regmap-irq to handle 1 IRQ feeding
 n chips

On 07/29/2012 02:36 PM, Mark Brown wrote:
> On Fri, Jul 27, 2012 at 01:01:56PM -0600, Stephen Warren wrote:
>> From: Stephen Warren <swarren@...dia.com>
>>
>> Some devices contain a single interrupt output, and multiple separate
>> interrupt controllers that all trigger that interrupt output, yet provide
>> no top-level interrupt controller/registers to allow determination of
>> which child interrupt controller caused the interrupt.
> 
> This isn't really anything to do with regmap, it's about implementing
> shared IRQ support for threaded interrupts.  This is generally useful
> and shouldn't be tied to regmap, it's common enough for hardware
> designers to want to use wired or interrupts and it's a limitation of
> Linux that it can't cope currently.
> 
> If are were going to implement it in regmap we shouldn't be faffing
> around setting up the virtual interrupts, we should just do the right
> thing and call round all the chips without bouncing it through the IRQ
> core.

OK, so more like how the max8907.c patch I posted did it than the
pre-existing arizona.c that I converted did it.

I had implemented this in regmap since you'd specifically mentioned
doing that. If I convert the code not to use separate IRQ domains for
this, would that be acceptable?

>> +static irqreturn_t regmaps_irq_thread(int irq, void *data)
>> +{
>> +	struct regmap_irq_chips_data *d = data;
>> +	int ret, i;
>> +
>> +	ret = pm_runtime_get_sync(d->dev);
>> +	if (ret < 0) {
> 
> This is conditional in the core regmap runtime PM support, it may be
> actively harmful if the device doesn't need it.

Hmmm. I actually don't see any pm_*() usage in regmap right now. I
assume this /is/ needed to convert arizona.c, since it's making these
calls today. I don't need it for max8907.c. Should I add another flag to
regmap_add_irq_chips() indicating whether this is needed, or ...?
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