From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from va3outboundpool.messaging.microsoft.com (va3ehsobe001.messaging.microsoft.com [216.32.180.11]) (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 322BE2C0356 for ; Tue, 18 Jun 2013 13:10:41 +1000 (EST) Received: from mail183-va3 (localhost [127.0.0.1]) by mail183-va3-R.bigfish.com (Postfix) with ESMTP id 3E1CDE01FD for ; Tue, 18 Jun 2013 03:10:37 +0000 (UTC) Received: from VA3EHSMHS031.bigfish.com (unknown [10.7.14.251]) by mail183-va3.bigfish.com (Postfix) with ESMTP id D913A1000A2 for ; Tue, 18 Jun 2013 03:09:49 +0000 (UTC) Message-ID: <51BFCF99.1010608@freescale.com> Date: Tue, 18 Jun 2013 11:10:17 +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: <1371514692.9073.12@snotra> In-Reply-To: <1371514692.9073.12@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 06/18/2013 08:18 AM, Scott Wood wrote: > On 06/17/2013 12:36:50 AM, Lian Minghuan-b31939 wrote: >> 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). > > Such functionality does not work on mpic v4.3. There are conflicting > requirements of contiguous MSIs (because PCI devices can use them that > way) and the inability to partition a single register (because they > all go to the same MPIC interrupt). > > Keep msi-available-ranges as is for older hardware, and just ignore it > (with a warning printed) if it's present on MPIC v4.3. > [Minghuan] Thanks for your guidance. But 'msireg' should be remained or removed? if remaining 'msiregs', it should be for all mpic or only for mpic v4.3? > -Scott