From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: IRQs in i2c-mpc.c From: Benjamin Herrenschmidt To: Kumar Gala In-Reply-To: References: <9e4733910711101144r3f8745dbs572aefa8658e1312@mail.gmail.com> <3DBBAC12-579B-4C1F-9C9E-D085FB22B687@kernel.crashing.org> <9e4733910711101516n64870e40rbd1fcbe3d123fcc3@mail.gmail.com> Content-Type: text/plain Date: Sun, 11 Nov 2007 17:26:20 +1100 Message-Id: <1194762380.21340.36.camel@pasglop> Mime-Version: 1.0 Cc: PowerPC dev list Reply-To: benh@kernel.crashing.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sat, 2007-11-10 at 17:18 -0600, Kumar Gala wrote: > On Nov 10, 2007, at 5:16 PM, Jon Smirl wrote: > > > On 11/10/07, Kumar Gala wrote: > >> Looking at the current driver it looks like we could get ride of if > >> check since the previous code checked the return of > >> platform_get_irq(). > > > > The code was a snippet from the larger patch that is converting i2c > > from being a platform driver to a of_platform driver. > > > > The question is, what to do about a missing IRQ tag in the device tree > > or a IRQ of zero. What is an error and what should be ignored, etc. > > I think the lack of an IRQ in the device tree should be an error. If > the IRQ value is zero, than its zero. virq 0 is always illegal so if platform_get_irq() returns 0, it can be safely treated as an error or the absence of irq, on both powerpc and x86. Ben.