From: Arnd Bergmann <arnd@arndb.de>
To: "Uwe =?iso-8859-1?q?Kleine-K=F6nig?=" 
	<u.kleine-koenig@pengutronix.de>
Subject: Re: [PATCH v3] irqchip: Add support for ARMv7-M's NVIC
Date: Fri, 19 Apr 2013 16:14:19 +0200
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Cc: Thomas Gleixner <tglx@linutronix.de>, kernel@pengutronix.de,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Jonathan Austin <jonathan.austin@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>
References: <1366214540-31166-1-git-send-email-u.kleine-koenig@pengutronix.de> <201304181138.13599.arnd@arndb.de> <20130419135107.GD15233@pengutronix.de>
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On Friday 19 April 2013, Uwe Kleine-K?nig wrote:
> On Thu, Apr 18, 2013 at 11:38:13AM +0200, Arnd Bergmann wrote:
> > On Thursday 18 April 2013, Uwe Kleine-K?nig wrote:
> > > That is, there are (INTLINESNUM + 1) * 32 irqs for INTLINESNUM < 15. For
> > > INTLINESNUM == 15 there are only 496 and not 16 * 32 == 512. That's the
> > > same on the gic (just with bigger numbers).
> > 
> > Ok, but since you are now using a linear domain, it doesn't actually hurt
> > to register 512 in that special case, right?
> Well, it depends if allocating space for 16 unused unsigned ints hurts
> (maybe not).

As long as SPARSE_IRQ is enabled, the space won't actually be allocated.

> And it makes mapping some irqs successfull while the irq
> doesn't really exist. But probably this doesn't hurt either because the
> problem already exists.
> 
> I don't care much. Is there another advantage beside saving a few source
> lines/instructions?

It just feels strange to read the value from hardware and then override
it anyway. But I agree it's not important either way.

	Arnd
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