Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966769AbWKTVVa (ORCPT ); Mon, 20 Nov 2006 16:21:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S966771AbWKTVVa (ORCPT ); Mon, 20 Nov 2006 16:21:30 -0500 Received: from mail.gmx.net ([213.165.64.20]:42219 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S966769AbWKTVV3 (ORCPT ); Mon, 20 Nov 2006 16:21:29 -0500 X-Authenticated: #20450766 Date: Mon, 20 Nov 2006 22:21:27 +0100 (CET) From: Guennadi Liakhovetski To: Russell King cc: Alan , Stefan Roese , linux-kernel@vger.kernel.org, linuxppc-embedded@ozlabs.org Subject: Re: [PATCH] serial: Use real irq on UART0 (IRQ = 0) on PPC4xx systems In-Reply-To: <20061120130455.GB22330@flint.arm.linux.org.uk> Message-ID: References: <200611201200.36780.ml@stefan-roese.de> <20061120114248.60bb0869@localhost.localdomain> <200611201255.37754.ml@stefan-roese.de> <20061120121015.2fb667d0@localhost.localdomain> <20061120130455.GB22330@flint.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1491 Lines: 36 On Mon, 20 Nov 2006, Russell King wrote: > > On Mon, 20 Nov 2006 12:54:32 +0100 (MET) > > Stefan Roese wrote: > > > Let's see, if I got this right. You mean that on such a platform, where 0 is a > > > valid physical IRQ, we should assign another value as virtual IRQ number (not > > > 0 and not -1 of course). And then the platform "pic" implementation should > > > take care of the remapping of these virtual IRQ numbers to the physical > > > numbers. > > Since IRQ0 is not valid, can we arrange for the generic interrupt > infrastructure to always fail it's allocation, and then remove the > utterly unused bloatful irq_desc[0] ? > > Didn't think so since x86 folk would scream. Wait a moment, x86 can > map IRQ0 to some other number for the timer interrupt, just like > other architectures are being forced to map their UART interrupts. I think, what Russell means, is this: #define is_real_interrupt(irq) ((irq) != NO_IRQ) where the NO_IRQ macro has been introduced a LONG time ago specifically for this purpose, and is conveniently defined on some platforms to (unsigned int)-1 or similar, including asm-powerpc/irq.h. And yes, this has been discussed MANY times. Thanks Guennadi --- Guennadi Liakhovetski - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/