From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Date: Wed, 24 Mar 2010 19:16:03 +0000 Subject: Re: [PATCH 01/10] irq: move some interrupt arch_* functions into Message-Id: <1269458163.28761.859.camel@localhost.localdomain> List-Id: References: <1269221770-9667-1-git-send-email-yinghai@kernel.org> <1269221770-9667-2-git-send-email-yinghai@kernel.org> <1269437531.10129.67616.camel@zakaz.uk.xensource.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Thomas Gleixner Cc: "lguest@ozlabs.org" , Jeremy Fitzhardinge , Rusty Russell , Paul Mundt , "linux-sh@vger.kernel.org" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , Jesse Barnes , "linuxppc-dev@ozlabs.org" , Ingo Molnar , Paul Mackerras , "Eric W. Biederman" , "H. Peter Anvin" , Ingo Molnar , Yinghai Lu , Andrew Morton On Wed, 2010-03-24 at 17:44 +0000, Thomas Gleixner wrote: > On Wed, 24 Mar 2010, Ian Campbell wrote: > > > On Mon, 2010-03-22 at 10:19 +0000, Thomas Gleixner wrote: > > > On Sun, 21 Mar 2010, Yinghai Lu wrote: > > > > > > > From: Ian Campbell > > > > > > > > Move arch_init_copy_chip_data and arch_free_chip_data into function > > > > pointers in struct irq_chip since they operate on irq_desc->chip_data. > > > > > > Not sure about that. These functions are solely used by x86 and there > > > is really no need to generalize them. > > > > I thought the idea of struct irq_chip was to allow the potential for > > multiple IRQ controllers in a system? Given that it seems that struct > > irq_desc->chip_data ought to be available for use by whichever struct > > irq_chip is managing a given interrupt. At the moment this is not > > possible because we step around the abstraction using these arch_* > > methods. > > Right, but you have exactly _ONE_ irq_chip associated to an irq_desc, > but that same irq_chip can be associated to several irq_descs. So > irq_desc->data is there to provide data for the irq_chip functions > depending on what irq they handle (e.g. base_address ...). > > irq_desc->chip_data is set when the irq_chip is assigned to the > irq_desc. > > So there is no point in having functions in irq_chip to set > irq_desc->chip_data. So how do you know which is the appropriate irq_chip specific function to call given an irq_desc that you want to copy/free/migrate? The contents of the chip_data pointer will take different forms for different irq_chips. The way the generic code is currently structured it appears you can't (or at least don't) just do a shallow copy by copying the irq_desc->chip_data pointer itself -- you need to do a deep copy using a function which understands that type of chip_data. How is this operation different to having pointers in irq_chip for enabling/disabling/masking interrupts for each irq_chip? Ian. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932849Ab0CXTQM (ORCPT ); Wed, 24 Mar 2010 15:16:12 -0400 Received: from smtp.citrix.com ([66.165.176.89]:16739 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754788Ab0CXTQK (ORCPT ); Wed, 24 Mar 2010 15:16:10 -0400 X-IronPort-AV: E=Sophos;i="4.51,302,1267419600"; d="scan'208";a="7680247" Subject: Re: [PATCH 01/10] irq: move some interrupt arch_* functions into struct irq_chip. From: Ian Campbell To: Thomas Gleixner CC: Yinghai Lu , Ingo Molnar , "H. Peter Anvin" , Andrew Morton , "Eric W. Biederman" , Jesse Barnes , "linux-kernel@vger.kernel.org" , Ingo Molnar , Jeremy Fitzhardinge , Benjamin Herrenschmidt , Paul Mackerras , "x86@kernel.org" , "linuxppc-dev@ozlabs.org" , Rusty Russell , "lguest@ozlabs.org" , Paul Mundt , "linux-sh@vger.kernel.org" In-Reply-To: References: <1269221770-9667-1-git-send-email-yinghai@kernel.org> <1269221770-9667-2-git-send-email-yinghai@kernel.org> <1269437531.10129.67616.camel@zakaz.uk.xensource.com> Content-Type: text/plain; charset="ISO-8859-1" Organization: Citrix Systems, Inc. Date: Wed, 24 Mar 2010 19:16:03 +0000 Message-ID: <1269458163.28761.859.camel@localhost.localdomain> MIME-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2010-03-24 at 17:44 +0000, Thomas Gleixner wrote: > On Wed, 24 Mar 2010, Ian Campbell wrote: > > > On Mon, 2010-03-22 at 10:19 +0000, Thomas Gleixner wrote: > > > On Sun, 21 Mar 2010, Yinghai Lu wrote: > > > > > > > From: Ian Campbell > > > > > > > > Move arch_init_copy_chip_data and arch_free_chip_data into function > > > > pointers in struct irq_chip since they operate on irq_desc->chip_data. > > > > > > Not sure about that. These functions are solely used by x86 and there > > > is really no need to generalize them. > > > > I thought the idea of struct irq_chip was to allow the potential for > > multiple IRQ controllers in a system? Given that it seems that struct > > irq_desc->chip_data ought to be available for use by whichever struct > > irq_chip is managing a given interrupt. At the moment this is not > > possible because we step around the abstraction using these arch_* > > methods. > > Right, but you have exactly _ONE_ irq_chip associated to an irq_desc, > but that same irq_chip can be associated to several irq_descs. So > irq_desc->data is there to provide data for the irq_chip functions > depending on what irq they handle (e.g. base_address ...). > > irq_desc->chip_data is set when the irq_chip is assigned to the > irq_desc. > > So there is no point in having functions in irq_chip to set > irq_desc->chip_data. So how do you know which is the appropriate irq_chip specific function to call given an irq_desc that you want to copy/free/migrate? The contents of the chip_data pointer will take different forms for different irq_chips. The way the generic code is currently structured it appears you can't (or at least don't) just do a shallow copy by copying the irq_desc->chip_data pointer itself -- you need to do a deep copy using a function which understands that type of chip_data. How is this operation different to having pointers in irq_chip for enabling/disabling/masking interrupts for each irq_chip? Ian. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH 01/10] irq: move some interrupt arch_* functions into struct irq_chip. From: Ian Campbell To: Thomas Gleixner In-Reply-To: References: <1269221770-9667-1-git-send-email-yinghai@kernel.org> <1269221770-9667-2-git-send-email-yinghai@kernel.org> <1269437531.10129.67616.camel@zakaz.uk.xensource.com> Content-Type: text/plain; charset="ISO-8859-1" Date: Wed, 24 Mar 2010 19:16:03 +0000 Message-ID: <1269458163.28761.859.camel@localhost.localdomain> MIME-Version: 1.0 Cc: "lguest@ozlabs.org" , Jeremy Fitzhardinge , Rusty Russell , Paul Mundt , "linux-sh@vger.kernel.org" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , Jesse Barnes , "linuxppc-dev@ozlabs.org" , Ingo Molnar , Paul Mackerras , "Eric W. Biederman" , "H. Peter Anvin" , Ingo Molnar , Yinghai Lu , Andrew Morton List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2010-03-24 at 17:44 +0000, Thomas Gleixner wrote: > On Wed, 24 Mar 2010, Ian Campbell wrote: > > > On Mon, 2010-03-22 at 10:19 +0000, Thomas Gleixner wrote: > > > On Sun, 21 Mar 2010, Yinghai Lu wrote: > > > > > > > From: Ian Campbell > > > > > > > > Move arch_init_copy_chip_data and arch_free_chip_data into function > > > > pointers in struct irq_chip since they operate on irq_desc->chip_data. > > > > > > Not sure about that. These functions are solely used by x86 and there > > > is really no need to generalize them. > > > > I thought the idea of struct irq_chip was to allow the potential for > > multiple IRQ controllers in a system? Given that it seems that struct > > irq_desc->chip_data ought to be available for use by whichever struct > > irq_chip is managing a given interrupt. At the moment this is not > > possible because we step around the abstraction using these arch_* > > methods. > > Right, but you have exactly _ONE_ irq_chip associated to an irq_desc, > but that same irq_chip can be associated to several irq_descs. So > irq_desc->data is there to provide data for the irq_chip functions > depending on what irq they handle (e.g. base_address ...). > > irq_desc->chip_data is set when the irq_chip is assigned to the > irq_desc. > > So there is no point in having functions in irq_chip to set > irq_desc->chip_data. So how do you know which is the appropriate irq_chip specific function to call given an irq_desc that you want to copy/free/migrate? The contents of the chip_data pointer will take different forms for different irq_chips. The way the generic code is currently structured it appears you can't (or at least don't) just do a shallow copy by copying the irq_desc->chip_data pointer itself -- you need to do a deep copy using a function which understands that type of chip_data. How is this operation different to having pointers in irq_chip for enabling/disabling/masking interrupts for each irq_chip? Ian.