From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753596AbaIZCeL (ORCPT ); Thu, 25 Sep 2014 22:34:11 -0400 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 User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.0.1 MIME-Version: 1.0 To: Thomas Gleixner CC: Bjorn Helgaas , , , Xinwei Hu , Wuyun , , Russell King , , , , , Arnd Bergmann , Konrad Rzeszutek Wilk , , Joerg Roedel , , , Benjamin Herrenschmidt , , , Sebastian Ott , "Tony Luck" , , "David S. Miller" , , Chris Metcalf , Ralf Baechle , Lucas Stach , David Vrabel , "Sergei Shtylyov" , Michael Ellerman , Thierry Reding , "Thomas Petazzoni" 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 X-Originating-IP: [10.177.27.212] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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