From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from metis.ext.pengutronix.de ([85.220.165.71]:56421 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934971AbeBMMgt (ORCPT ); Tue, 13 Feb 2018 07:36:49 -0500 Message-ID: <1518525395.2744.14.camel@pengutronix.de> Subject: Re: [PATCH v6 0/9] PCI: dwc: MSI-X feature From: Lucas Stach To: Lorenzo Pieralisi , Gustavo Pimentel Cc: "marc.zyngier@arm.com" , "Joao.Pinto@synopsys.com" , "bhelgaas@google.com" , "jingoohan1@gmail.com" , "kishon@ti.com" , "linux-pci@vger.kernel.org" , "m-karicheri2@ti.com" , "thomas.petazzoni@free-electrons.com" , "minghuan.Lian@freescale.com" , "mingkai.hu@freescale.com" , "tie-fei.zang@freescale.com" , "hongxing.zhu@nxp.com" , "niklas.cassel@axis.com" , "jesper.nilsson@axis.com" , "wangzhou1@hisilicon.com" , "gabriele.paoloni@huawei.com" , "svarbanov@mm-sol.com" , "nsekhar@ti.com" Date: Tue, 13 Feb 2018 13:36:35 +0100 In-Reply-To: <20180213122920.GB8981@e107981-ln.cambridge.arm.com> References: <20180212122334.GA25396@e107981-ln.cambridge.arm.com> <47720ab7-1eb5-0605-5711-80595b358f7d@synopsys.com> <20180213122920.GB8981@e107981-ln.cambridge.arm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org List-ID: Am Dienstag, den 13.02.2018, 12:29 +0000 schrieb Lorenzo Pieralisi: > On Mon, Feb 12, 2018 at 06:14:29PM +0000, Gustavo Pimentel wrote: > > Hi Lorenzo, > > > > On 12/02/2018 12:23, Lorenzo Pieralisi wrote: > > > On Fri, Jan 26, 2018 at 04:35:35PM +0000, Gustavo Pimentel wrote: > > > > Replaces the use of IRQ domain hierarchy by the IRQ chained > > > > used by > > > > pcie-designware and each SoC specific driver in order to allow > > > > new and > > > > complex features like MSI-X. > > > > > > > > Adds Synopsys Root Complex support for MSI-X feature. > > > > > > Hi Gustavo, > > > > > > please CC me for future patch versions. I have a question for > > > you, > > > the series definitely looks like it is going in the right > > > direction > > > but I do not understand the cover letter. > > > > > > - You are not replacing the IRQ domain hierarchy, you are > > > actually > > >   introducing it properly. It may be just nomenclature but I > > > though > > >   I would mention that. > > > - I really do not understand why this series is advertised as > > >   "implementing MSI-X". I want to understand why MSI-X it is not > > >   currently supported and why this series would enable it, I > > >   honestly do not understand the reasoning behind this, it looks > > >   a bit fuzzy. > > > > > > Please note I am just asking clarifications on the $SUBJECT for > > > my own > > > understanding, the series is definitely the right thing to do and > > > I am > > > happy to target v4.17 for it. > > > > Marc Zyngier also pointed out like you that the description is > > confusing and > > does not correspond to what is done in the code and now I also see > > it now. > > > > Please fell free to review and point out something wrong, only in > > this way can I > > evolve. :) > > Sure. Let's start by discussing this: > > https://patchwork.kernel.org/patch/5708521/ > > If it is a HW issue your patches can't solve it. If it is a SW issue > patch above (and current mainline code - commit 19c5392eb1c1) is > wrong. > > Before updating the code I want to understand what the problem is > with > MSI-X in current mainline. > > To be as clear as I can: this series is doing the *right* thing, I > want > to understand what the current driver is doing with MSIs and why, so > that we can help you update the code correctly. It's partly a software issue and partly a wrong understanding of MSI-X on my side at the time. The DW hardware doesn't support different MSI target addresses for individual MSIs, but that's just a optional feature of MSI-X and not required to implement them correctly. Enabling of MSI-X on the DW hardware via a proper software implementation is fine. Regards, Lucas