From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from tx2outboundpool.messaging.microsoft.com (tx2ehsobe004.messaging.microsoft.com [65.55.88.14]) (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 2B4E62C02CF for ; Wed, 19 Jun 2013 02:22:49 +1000 (EST) Received: from mail97-tx2 (localhost [127.0.0.1]) by mail97-tx2-R.bigfish.com (Postfix) with ESMTP id C52B2320071 for ; Tue, 18 Jun 2013 16:22:44 +0000 (UTC) Received: from TX2EHSMHS034.bigfish.com (unknown [10.9.14.230]) by mail97-tx2.bigfish.com (Postfix) with ESMTP id 84AA140048 for ; Tue, 18 Jun 2013 16:22:31 +0000 (UTC) Date: Tue, 18 Jun 2013 11:22:25 -0500 From: Scott Wood Subject: Re: [PATCH 5/5] powerpc/fsl_msi: add 'msiregs' kernel parameter To: Lian Minghuan-b31939 References: <1371514692.9073.12@snotra> <51BFCF99.1010608@freescale.com> In-Reply-To: <51BFCF99.1010608@freescale.com> (from B31939@freescale.com on Mon Jun 17 22:10:17 2013) Message-ID: <1371572545.9073.21@snotra> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; delsp=Yes; 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: , On 06/17/2013 10:10:17 PM, Lian Minghuan-b31939 wrote: > Hi Scott, >=20 > please see my comments inline. >=20 > On 06/18/2013 08:18 AM, Scott Wood wrote: >> On 06/17/2013 12:36:50 AM, Lian Minghuan-b31939 wrote: >>> Hi Scott, >>>=20 >>> please see my comments inline. >>>=20 >>> 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. >>>>>=20 >>>>> 2. Add 'msiregs' kernel parameter instead of =20 >>>>> 'msi-available-ranges' >>>>> functionality. >>>>=20 >>>> The reason we used a device tree property was because this is for =20 >>>> virtualization and AMP scenarios where this instance of Linux does =20 >>>> not own all of the MSI registers. >>>>=20 >>>> I don't see any reasonable way to partition an MPIC v4.3 MSI group =20 >>>> -- but there are more groups, so it's not that bad. What's the use =20 >>>> case for this patch? >>>>=20 >>> [Minghuan] I do not known any case about this patch. I add =20 >>> 'msiregs' just for achieving "msi-available-ranges" functionality. =20 >>> I do not want to remove partition functionality when updating to =20 >>> mpic4.3, although I do not see virtualization and AMP cases on =20 >>> T4(KVM does not need this functionality). >>=20 >> Such functionality does not work on mpic v4.3. There are =20 >> conflicting requirements of contiguous MSIs (because PCI devices can =20 >> use them that way) and the inability to partition a single register =20 >> (because they all go to the same MPIC interrupt). >>=20 >> Keep msi-available-ranges as is for older hardware, and just ignore =20 >> it (with a warning printed) if it's present on MPIC v4.3. >>=20 > [Minghuan] Thanks for your guidance. > But 'msireg' should be remained or removed? Removed. -Scott=