From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933279Ab1LFLFS (ORCPT ); Tue, 6 Dec 2011 06:05:18 -0500 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:49493 "EHLO earthlight.etchedpixels.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933147Ab1LFLFQ (ORCPT ); Tue, 6 Dec 2011 06:05:16 -0500 Date: Tue, 6 Dec 2011 11:05:54 +0000 From: Alan Cox To: Russell King - ARM Linux Cc: Dave Martin , Nicolas Pitre , Benjamin Herrenschmidt , Linus Torvalds , Anton Vorontsov , Stephen Rothwell , Andrew Morton , devicetree-discuss@lists.ozlabs.org, LKML , linux-ide@vger.kernel.org, Randy Dunlap , linux-next@vger.kernel.org, Ingo Molnar , Jeff Garzik , Pawel Moll , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] ata: Don't use NO_IRQ in pata_of_platform driver Message-ID: <20111206110554.53bddd14@lxorguk.ukuu.org.uk> In-Reply-To: <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> <20111206104654.GN14542@n2100.arm.linux.org.uk> X-Mailer: Claws Mail 3.7.9 (GTK+ 2.24.7; x86_64-redhat-linux-gnu) Face: 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 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > 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. The ISA bus space is non-discoverable so that doesn't make any sense. > 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. x86 has an internal invisible IRQ 0 on some platforms. It's never exposed beyond the arch code. > 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. Actually it would be about ten minutes work to remap it to some other number that isn't used. It never goes via request_irq or via any core or driver layer code however. In the ARM case the same is going to be true. If you have IRQ 0 plumbing that only goes internally in the arch/arm code - eg an ARM with IRQ 0 wired to something totally arch specific and non-driver then it's not going to break and like the internals of x86 doesn't matter. > When x86 sorts this out, there _might_ be some more motivation to take > such comments seriously. Until then it's more like a joke. Pity you feel that way, but if ARM wants to continue to break more and more as we clean up NO_IRQ for everything else that's your privilege, but don't expect any sympathy. Alan