From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from moutng.kundenserver.de ([212.227.126.171]:50302 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755139Ab2FNLG6 (ORCPT ); Thu, 14 Jun 2012 07:06:58 -0400 From: Arnd Bergmann To: Thierry Reding Subject: Re: [PATCH v2 07/10] ARM: tegra: pcie: Add device tree support Date: Thu, 14 Jun 2012 11:06:48 +0000 Cc: linux-arm-kernel@lists.infradead.org, Mitch Bradley , Russell King , Stephen Warren , linux-pci@vger.kernel.org, devicetree-discuss@lists.ozlabs.org, Jesse Barnes , Rob Herring , Colin Cross , linux-tegra@vger.kernel.org References: <1339427118-32263-1-git-send-email-thierry.reding@avionic-design.de> <201206141025.09325.arnd@arndb.de> <20120614103127.GA15904@avionic-0098.mockup.avionic-design.de> In-Reply-To: <20120614103127.GA15904@avionic-0098.mockup.avionic-design.de> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Message-Id: <201206141106.49142.arnd@arndb.de> Sender: linux-pci-owner@vger.kernel.org List-ID: On Thursday 14 June 2012, Thierry Reding wrote: > On Thu, Jun 14, 2012 at 10:25:09AM +0000, Arnd Bergmann wrote: > > On Thursday 14 June 2012, Thierry Reding wrote: > > > > > > > > I believe you will need an "interrupt-map" property here, to map the host > > > > interrupts to the INTA-INTD lines of the attached devices. > > > > > > Legacy interrupts are something I cannot test at all because I have no > > > hardware that supports them. > > > > Hmm, I thought all PCIe hardware has to support them when you do not > > enable MSI. What hardware do you have then? > > The TEC (Tamonten Evaluation Carrier) has an FPGA which is connected to one > of the Tegra PCIe ports and it only supports MSIs. Ah, I see. FPGA based devices often have incomplete PCI support so that explains why you can't test it. The board also appears to have a PCIe mini port though, so anything that you could plug in there should also support LSI interrupts. > > > > I'm not sure whether we want to have a device_type="pciex" property here. > > > > powerpc and sparc seem to use that information, to distinguish a pcie > > > > bus from pci or cardbus. > > > > > > That'd be rather useless information given that the Tegra is unlikely to > > > support either PCI or CardBus at some point. > > > > But the generic code does not know that. > > True. Still there's not much generic code on ARM, so maybe it'd be better to > add it along with the corresponding code? I hope we can make the PCI host probing architecture independent one day, instead of each architecture implementing their own. I'd say better put that property in there so we don't have to change it in case the future generic code will need it. It is part of the binding at http://www.openfirmware.org/1275/bindings/pci/pci-express.txt after all. Note that we should generally not make /code/ be written with the anticipation of a future extension, but anything that concerns interfaces to code outside of the kernel (firmware or user space) is best written in a conservative way to allow later changes. Arnd