From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7A477C43387 for ; Tue, 18 Dec 2018 15:32:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5695F2133F for ; Tue, 18 Dec 2018 15:32:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726700AbeLRPck (ORCPT ); Tue, 18 Dec 2018 10:32:40 -0500 Received: from foss.arm.com ([217.140.101.70]:48238 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726717AbeLRPck (ORCPT ); Tue, 18 Dec 2018 10:32:40 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BFCF8A78; Tue, 18 Dec 2018 07:32:39 -0800 (PST) Received: from e107981-ln.cambridge.arm.com (e107981-ln.cambridge.arm.com [10.1.197.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 85AB23F5C0; Tue, 18 Dec 2018 07:32:37 -0800 (PST) Date: Tue, 18 Dec 2018 15:32:32 +0000 From: Lorenzo Pieralisi To: Jianjun Wang Cc: Bjorn Helgaas , ryder.lee@mediatek.com, robh+dt@kernel.org, matthias.bgg@gmail.com, linux-pci@vger.kernel.org, mark.rutland@arm.com, devicetree@vger.kernel.org, youlin.pei@mediatek.com, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, honghui.zhang@mediatek.com, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 2/2] PCI: mediatek: Add controller support for MT7629 Message-ID: <20181218153232.GA6715@e107981-ln.cambridge.arm.com> References: <1544058553-10936-1-git-send-email-jianjun.wang@mediatek.com> <1544058553-10936-3-git-send-email-jianjun.wang@mediatek.com> <20181213145517.GB4701@google.com> <1545034779.8528.8.camel@mhfsdcap03> <20181217143247.GK20725@google.com> <20181217154645.GA24864@e107981-ln.cambridge.arm.com> <1545124764.25199.3.camel@mhfsdcap03> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1545124764.25199.3.camel@mhfsdcap03> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Dec 18, 2018 at 05:19:24PM +0800, Jianjun Wang wrote: > On Mon, 2018-12-17 at 15:46 +0000, Lorenzo Pieralisi wrote: > > On Mon, Dec 17, 2018 at 08:32:47AM -0600, Bjorn Helgaas wrote: > > > On Mon, Dec 17, 2018 at 04:19:39PM +0800, Jianjun Wang wrote: > > > > On Thu, 2018-12-13 at 08:55 -0600, Bjorn Helgaas wrote: > > > > > On Thu, Dec 06, 2018 at 09:09:13AM +0800, Jianjun Wang wrote: > > > > > > The read value of BAR0 is 0xffff_ffff, it's size will be calculated as 4GB > > > > > > in arm64 but bogus alignment values at arm32, the pcie device and devices > > > > > > behind this bridge will not be enabled. Fix it's BAR0 resource size to > > > > > > guarantee the pcie devices will be enabled correctly. > > > > > > > > > > So this is a hardware erratum? Per spec, a memory BAR has bit 0 hardwired > > > > > to 0, and an IO BAR has bit 1 hardwired to 0. > > > > > > > > Yes, it only works properly on 64bit platform. > > > > > > I don't understand. BARs are supposed to work the same regardless of > > > whether it's a 32- or 64-bit platform. If this is a workaround for a > > > hardware defect, please just say that explicitly. > > > > I do not understand this either. First thing to do is to describe the > > problem properly so that we can actually find a solution to it. > > > > Lorenzo > > This BAR0 is a 64-bit memory BAR, the HW default values for this BAR is > 0xffff_ffff_0000_0000 and it could not be changed except by config write > operation. > > The calculated BAR size will be 0 in 32-bit platform since the > phys_addr_t is a 32bit value in 32-bit platform. > > Actually MediaTek's HW does not using this BAR0, just omit it when > assign resource is totally fine. > > When assign the resource for each device, software will check the > resource alignment first, and the resource of length zero will be > regarded as a bogus alignment resource, it will be ignored and won't > claim a resource parent for it. > > When drivers try to enable the PCIe devices, the software will enable > it's resources, but it will return an error number when found a > unclaimed resource, in that case, the flow of enable devices will be > interrupted and PCIe devices won't work properly. As a starting point, please provide kernel logs for both 64-bit and 32-bit platforms (without this patch applied) and also a: cat /proc/iomem and lspci output for both configurations. Thanks, Lorenzo