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=-20.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 1FFB9C4338F for ; Mon, 9 Aug 2021 16:25:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 002AE60041 for ; Mon, 9 Aug 2021 16:25:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232638AbhHIQZt (ORCPT ); Mon, 9 Aug 2021 12:25:49 -0400 Received: from foss.arm.com ([217.140.110.172]:36284 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232310AbhHIQZP (ORCPT ); Mon, 9 Aug 2021 12:25:15 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D5FD6D6E; Mon, 9 Aug 2021 09:24:51 -0700 (PDT) Received: from [192.168.122.166] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5C00E3F718; Mon, 9 Aug 2021 09:24:51 -0700 (PDT) Subject: Re: [PATCH 3/3] PCI/ACPI: Add new quirk detection, enable bcm2711 To: Rob Herring Cc: Bjorn Helgaas , PCI , Lorenzo Pieralisi , Nicolas Saenz Julienne , Bjorn Helgaas , "Rafael J. Wysocki" , Len Brown , Krzysztof Wilczynski , Florian Fainelli , "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" , "open list:ACPI FOR ARM64 (ACPI/arm64)" , linux-arm-kernel , "moderated list:BROADCOM BCM2835 ARM ARCHITECTURE" , "linux-kernel@vger.kernel.org" References: <20210806221256.GA1891371@bjorn-Precision-5520> <5f4f484b-9eef-2722-405d-a7ff6259aa0f@arm.com> From: Jeremy Linton Message-ID: Date: Mon, 9 Aug 2021 11:24:46 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Thanks for looking at this. On 8/9/21 10:27 AM, Rob Herring wrote: > On Fri, Aug 6, 2021 at 6:35 PM Jeremy Linton wrote: >> >> Hi, >> >> Thanks for looking at this. >> >> On 8/6/21 5:12 PM, Bjorn Helgaas wrote: >>> In subject, this or similar would match history: >>> >>> PCI/ACPI: Add Broadcom bcm2711 MCFG quirk >>> >>> On Thu, Aug 05, 2021 at 04:12:00PM -0500, Jeremy Linton wrote: >>>> Now that we have a bcm2711 quirk, we need to be able to >>>> detect it when the MCFG is missing. Use a namespace >>>> property as an alternative to the MCFG OEM. >>> >>> Rewrap to use ~75 columns. >>> >>> Mention the DT namespace property here. >>> >>>> Signed-off-by: Jeremy Linton >>>> --- >>>> drivers/acpi/pci_mcfg.c | 14 ++++++++++++++ >>>> 1 file changed, 14 insertions(+) >>>> >>>> diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c >>>> index 53cab975f612..7d77fc72c2a4 100644 >>>> --- a/drivers/acpi/pci_mcfg.c >>>> +++ b/drivers/acpi/pci_mcfg.c >>>> @@ -169,6 +169,9 @@ static struct mcfg_fixup mcfg_quirks[] = { >>>> ALTRA_ECAM_QUIRK(1, 13), >>>> ALTRA_ECAM_QUIRK(1, 14), >>>> ALTRA_ECAM_QUIRK(1, 15), >>>> + >>>> + { "bcm2711", "", 0, 0, MCFG_BUS_ANY, &bcm2711_pcie_ops, >>>> + DEFINE_RES_MEM(0xFD500000, 0xA000) }, >>>> }; >>>> >>>> static char mcfg_oem_id[ACPI_OEM_ID_SIZE]; >>>> @@ -198,8 +201,19 @@ static void pci_mcfg_apply_quirks(struct acpi_pci_root *root, >>>> u16 segment = root->segment; >>>> struct resource *bus_range = &root->secondary; >>>> struct mcfg_fixup *f; >>>> + const char *soc; >>>> int i; >>>> >>>> + /* >>>> + * This could be a machine with a PCI/SMC conduit, >>>> + * which means it doens't have MCFG. Get the machineid from >>>> + * the namespace definition instead. >>> >>> s/SMC/SMCCC/ ? Cover letter uses SMCCC (not sure it's relevant anyway) >>> s/doens't/doesn't/ >>> >>> Rewrap comment to use ~80 columns. >>> >>> Seems pretty reasonable that a platform without standard ECAM might >>> not have MCFG, since MCFG basically implies ECAM. >> >> >> Sure, on all the above comments. >> >>> >>> Is "linux,pcie-quirk" the right property to look for? It doesn't >>> sound very generic, and it doesn't sound like anything related to >>> ECAM. Is it new? I don't see it in the tree yet. Should it be in >>> Documentation/devicetree/bindings/pci/pci.txt so we don't get a >>> different property name for every new platform? > > No, it should not be in pci.txt. Nothing to do with DT and I don't > review ACPI bindings (someone should) if I can help it. That is the intention of the uefi properties registry I referred to earlier. It has a code first model too, which allows us to review it here and then update the document with the property and the intended behavior. > >> Yes, I made it up. Someone else commented about the "linux," partially >> because it should be "linux-" to conform with >> https://github.com/UEFI/DSD-Guide. But also in the same context of it >> being linux specific. I think that guide is where it should end up, >> rather than the devicetree bindings. >> >> I guess we can request addition to the uefi- but that seems like a >> mistake this is really (hopefully?) a Linux specific properly as other >> OS's will simply use the SMC. I think we could request another prefix if >> we come up with a good one and think it belongs in that guide. > > It's only Linux specific until it's not. > > What happens when there's a second PCIe quirk here? Say what the quirk > is (and not in terms of Linux policy). This is really just a stand in for the existing MCFG oem id, its an identifier to key off, nothing else. Maybe a better name is "linux-ecam-quirk-id" or something to that effect? > > Don't you know the device here and can imply all this (like implying > off of 'compatible' in DT)? Adding properties to address issues > creates compatibility issues. Maybe not an issue in this case if the > firmware is not stable, but not a good practice to be in. Yes, and no, I think there was some discussion a few years back about using non standard HID's for these nonstandard implementations, but that was discouraged at the time in favor of using the standard identifiers and and keying off a Soc/platform specific ID to enable a "quirk". Given we are a bit far down that path and the decision was made to continue down it (rather than solving much of it with a new firmware interface) this seems like the straightforward solution. The vast majority of these are SoC specific, and just minor tweaks for alignment/etc. Given its an ACPI/UEFI machine we are already hiding a lot of the platform specific behavior for configuring the bridge/etc that might require DT like properties in the firmware. Thanks again.