From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yijing Wang Subject: Re: [PATCH v2 06/22] PCI/MSI: Introduce weak arch_find_msi_chip() to find MSI chip Date: Fri, 26 Sep 2014 10:33:24 +0800 Message-ID: <5424D074.60102@huawei.com> References: <1411614872-4009-1-git-send-email-wangyijing@huawei.com> <1411614872-4009-7-git-send-email-wangyijing@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from szxga02-in.huawei.com ([119.145.14.65]:7739 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753041AbaIZCeJ (ORCPT ); Thu, 25 Sep 2014 22:34:09 -0400 In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Thomas Gleixner Cc: Bjorn Helgaas , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Xinwei Hu , Wuyun , linux-arm-kernel@lists.infradead.org, Russell King , linux-arch@vger.kernel.org, arnab.basu@freescale.com, Bharat.Bhushan@freescale.com, x86@kernel.org, Arnd Bergmann , Konrad Rzeszutek Wilk , xen-devel@lists.xenproject.org, Joerg Roedel , iommu@lists.linux-foundation.org, linux-mips@linux-mips.org, Benjamin Herrenschmidt , linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, Sebastian Ott , Tony Luck , linux-ia64@vger.kernel.org, "David S. Miller" , sparclinux@vger.kernel.org, Chris Metcalf On 2014/9/25 18:38, Thomas Gleixner wrote: > On Thu, 25 Sep 2014, Yijing Wang wrote: > >> Introduce weak arch_find_msi_chip() to find the match msi_chip. >> Currently, MSI chip associates pci bus to msi_chip. Because in >> ARM platform, there may be more than one MSI controller in system. >> Associate pci bus to msi_chip help pci device to find the match >> msi_chip and setup MSI/MSI-X irq correctly. But in other platform, >> like in x86. we only need one MSI chip, because all device use >> the same MSI address/data and irq etc. So it's no need to associate >> pci bus to MSI chip, just use a arch function, arch_find_msi_chip() >> to return the MSI chip for simplicity. The default weak >> arch_find_msi_chip() used in ARM platform, find the MSI chip >> by pci bus. > > This is really backwards. On one hand you try to get rid of the weak > arch functions zoo and then you invent new ones for no good > reason. Why can't x86 store the chip in the pci bus? Hi Thomas, I introduced this weak function , because I thought all platforms except arm always have only one msi chip, and I hoped to provide a simplest solution, less code changes. I consider several solutions to associate msi chip and PCI device. In my reply to Thierry in first reply, http://marc.info/?l=linux-pci&m=141169658208255&w=2 Could you give me some advices ? Thanks! Yijing. > > Looking deeper, I'm questioning the whole notion of different > msi_chips. Are this really different MSI controllers with a different > feature set or are this defacto multiple instances of the same > controller which just need a different data set? > > Thanks, > > tglx > > . > -- Thanks! Yijing From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from szxga02-in.huawei.com ([119.145.14.65]:7739 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753041AbaIZCeJ (ORCPT ); Thu, 25 Sep 2014 22:34:09 -0400 Message-ID: <5424D074.60102@huawei.com> Date: Fri, 26 Sep 2014 10:33:24 +0800 From: Yijing Wang MIME-Version: 1.0 Subject: Re: [PATCH v2 06/22] PCI/MSI: Introduce weak arch_find_msi_chip() to find MSI chip References: <1411614872-4009-1-git-send-email-wangyijing@huawei.com> <1411614872-4009-7-git-send-email-wangyijing@huawei.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Thomas Gleixner Cc: Bjorn Helgaas , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Xinwei Hu , Wuyun , linux-arm-kernel@lists.infradead.org, Russell King , linux-arch@vger.kernel.org, arnab.basu@freescale.com, Bharat.Bhushan@freescale.com, x86@kernel.org, Arnd Bergmann , Konrad Rzeszutek Wilk , xen-devel@lists.xenproject.org, Joerg Roedel , iommu@lists.linux-foundation.org, linux-mips@linux-mips.org, Benjamin Herrenschmidt , linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, Sebastian Ott , Tony Luck , linux-ia64@vger.kernel.org, "David S. Miller" , sparclinux@vger.kernel.org, Chris Metcalf , Ralf Baechle , Lucas Stach , David Vrabel , Sergei Shtylyov , Michael Ellerman , Thierry Reding , Thomas Petazzoni Message-ID: <20140926023324.ehpOutRlC6y0wopnCQOmVPQxTJqRuL23UQGYnmAco2o@z> On 2014/9/25 18:38, Thomas Gleixner wrote: > On Thu, 25 Sep 2014, Yijing Wang wrote: > >> Introduce weak arch_find_msi_chip() to find the match msi_chip. >> Currently, MSI chip associates pci bus to msi_chip. Because in >> ARM platform, there may be more than one MSI controller in system. >> Associate pci bus to msi_chip help pci device to find the match >> msi_chip and setup MSI/MSI-X irq correctly. But in other platform, >> like in x86. we only need one MSI chip, because all device use >> the same MSI address/data and irq etc. So it's no need to associate >> pci bus to MSI chip, just use a arch function, arch_find_msi_chip() >> to return the MSI chip for simplicity. The default weak >> arch_find_msi_chip() used in ARM platform, find the MSI chip >> by pci bus. > > This is really backwards. On one hand you try to get rid of the weak > arch functions zoo and then you invent new ones for no good > reason. Why can't x86 store the chip in the pci bus? Hi Thomas, I introduced this weak function , because I thought all platforms except arm always have only one msi chip, and I hoped to provide a simplest solution, less code changes. I consider several solutions to associate msi chip and PCI device. In my reply to Thierry in first reply, http://marc.info/?l=linux-pci&m=141169658208255&w=2 Could you give me some advices ? Thanks! Yijing. > > Looking deeper, I'm questioning the whole notion of different > msi_chips. Are this really different MSI controllers with a different > feature set or are this defacto multiple instances of the same > controller which just need a different data set? > > Thanks, > > tglx > > . > -- Thanks! Yijing