From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from co9outboundpool.messaging.microsoft.com (co9ehsobe003.messaging.microsoft.com [207.46.163.26]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "MSIT Machine Auth CA 2" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 1FA5F2C0174 for ; Mon, 17 Jun 2013 15:36:31 +1000 (EST) Received: from mail174-co9 (localhost [127.0.0.1]) by mail174-co9-R.bigfish.com (Postfix) with ESMTP id 5A29E9800DE for ; Mon, 17 Jun 2013 05:36:28 +0000 (UTC) Received: from CO9EHSMHS015.bigfish.com (unknown [10.236.132.229]) by mail174-co9.bigfish.com (Postfix) with ESMTP id 140FC34006E for ; Mon, 17 Jun 2013 05:36:26 +0000 (UTC) Message-ID: <51BEA072.1040902@freescale.com> Date: Mon, 17 Jun 2013 13:36:50 +0800 From: Lian Minghuan-b31939 MIME-Version: 1.0 To: Scott Wood Subject: Re: [PATCH 5/5] powerpc/fsl_msi: add 'msiregs' kernel parameter References: <1371194159-17332-1-git-send-email-Minghuan.Lian@freescale.com> <1371194159-17332-5-git-send-email-Minghuan.Lian@freescale.com> <1371248034.2996.18@snotra> In-Reply-To: <1371248034.2996.18@snotra> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Cc: Minghuan Lian , linuxppc-dev@lists.ozlabs.org, Zang Roy-R61911 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Scott, please see my comments inline. On 06/15/2013 06:13 AM, Scott Wood wrote: > On 06/14/2013 02:15:59 AM, Minghuan Lian wrote: >> 1. Only MSIIR1 can index 16 MSI registers, but when using MSIIR1 >> the IRQs of a register are not continuous. for example, the first >> register irq values are 0x0, 0x10, 0x20, 0x30 ... 0x1f0. So it >> is hard to use 'msi-available-ranges' property to indicate the >> available ranges and 'msi-available-ranges' property has been >> removed from dts node, so this patch removes the related code. >> >> 2. Add 'msiregs' kernel parameter instead of 'msi-available-ranges' >> functionality. > > The reason we used a device tree property was because this is for > virtualization and AMP scenarios where this instance of Linux does not > own all of the MSI registers. > > I don't see any reasonable way to partition an MPIC v4.3 MSI group -- > but there are more groups, so it's not that bad. What's the use case > for this patch? > [Minghuan] I do not known any case about this patch. I add 'msiregs' just for achieving "msi-available-ranges" functionality. I do not want to remove partition functionality when updating to mpic4.3, although I do not see virtualization and AMP cases on T4(KVM does not need this functionality). If you hope to keep 'msi-available-ranges' property for older mpic, can I add 'msi-available-regs' property for mpic4.3. Using 'msi-available-regs' to implement partition is similar to 'msi-available-ranges'. When considering the consistency, 'msi-available-regs' is better than msiregs. > -Scott