From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH] ata: Don't use NO_IRQ in pata_of_platform driver Date: Tue, 6 Dec 2011 10:46:54 +0000 Message-ID: <20111206104654.GN14542@n2100.arm.linux.org.uk> References: <20111202192618.GC3037@localhost.localdomain> <1322867573.11728.22.camel@pasglop> <20111205161157.GA27550@localhost.localdomain> <20111205180253.GB29812@localhost.localdomain> <20111205192605.GD29812@localhost.localdomain> <20111206093709.GB2274@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20111206093709.GB2274-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: Dave Martin Cc: Nicolas Pitre , Stephen Rothwell , Pawel Moll , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, LKML , Jeff Garzik , linux-ide-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Randy Dunlap , linux-next-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Anton Vorontsov , Andrew Morton , Linus Torvalds , Ingo Molnar , Alan Cox List-Id: devicetree@vger.kernel.org On Tue, Dec 06, 2011 at 09:37:09AM +0000, Dave Martin wrote: > To clarify, you're suggesting that the meanings of all other IRQ values > would not change initially? (i.e., we remap HW irq 0, if there is one, > to some other random number but have a 1:1 mapping for everything else). Even better. Avoid the first 16 IRQ numbers altogether - so that ISA drivers which have these numbers hard-encoded in them will see failures if they're expecting standard ISA IRQ numbering. We already do that with the GIC, partly because of the hardware design. We do that on Footbridge based systems, because they may or may not have a real ISA IRQ controller. But.. let's make one thing clear: Alan Cox and Linus have been going on about how IRQ0 should not be used. Let's be crystal clear: even x86 uses IRQ0. It happens to be the PIC timer, and that gets claimed early on during the x86 boot. So please don't tell me that x86 avoids IRQ0. It doesn't. It just happens that x86 never shows IRQ0 to anything but the i8253 PIC driver. So lets see how x86 squeels if we make the i8253 PIC driver reject IRQ0. I bet that there'd be absolute fury at such a suggestion. When x86 sorts this out, there _might_ be some more motivation to take such comments seriously. Until then it's more like a joke.