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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3583AC3F6B0 for ; Wed, 17 Aug 2022 16:42:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240132AbiHQQmz (ORCPT ); Wed, 17 Aug 2022 12:42:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53770 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237506AbiHQQmw (ORCPT ); Wed, 17 Aug 2022 12:42:52 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76BBD88DFB; Wed, 17 Aug 2022 09:42:51 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 0F944B81E25; Wed, 17 Aug 2022 16:42:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E9BBC433D6; Wed, 17 Aug 2022 16:42:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1660754568; bh=+wEnZVI2aj40wim23BMsG+ci2KQg9to47RsgHXVHy10=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YpvpIKT4XzsirkSD5uvjCpB+/1pIK+WsuRzW1OyY4JFHJM/UPgkTU0Dyof3gdxlD+ N9UeWOT6DqR/F02nr8dTesCV9NATI2TGSUYB/R9tBGzxXPSg7QngOCs5ui5IBs+gJK rLwzJXJaLD1zhLxBAV94ZgMrFc9tma23ROcaLTcjfUc11WtX2f8GtAX3UuppT+RZ9D D/K4io2T2RJfGjy4B2YcPEiR8BzL+YTRRIVdYftQPQGNTKD9lAaaBVMtxJbptx87kx xeTN8Ihpf1nOpMTw7H4aCfYwqI9wj9ciPuFbzK99E0x0QcrXw5JhOlTMGBiJ4wrrEc osemWEeY22khw== Received: by pali.im (Postfix) id AAA9C739; Wed, 17 Aug 2022 18:42:45 +0200 (CEST) Date: Wed, 17 Aug 2022 18:42:45 +0200 From: Pali =?utf-8?B?Um9ow6Fy?= To: Michael Ellerman Cc: Benjamin Herrenschmidt , Paul Mackerras , Christophe Leroy , =?utf-8?Q?C=C3=A9dric?= Le Goater , Nick Child , Bjorn Helgaas , linuxppc-dev@lists.ozlabs.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 5/5] powerpc/pci: Add config option for using all 256 PCI buses Message-ID: <20220817164245.qanxklpavge3shcm@pali> References: <20220706104308.5390-1-pali@kernel.org> <20220706104308.5390-6-pali@kernel.org> <20220721222145.rzgthbwoselx2l43@pali> <875yjkb0ht.fsf@mpe.ellerman.id.au> <20220726111001.a2upqf5m5welcla6@pali> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220726111001.a2upqf5m5welcla6@pali> User-Agent: NeoMutt/20180716 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 26 July 2022 13:10:01 Pali Rohár wrote: > On Tuesday 26 July 2022 21:02:22 Michael Ellerman wrote: > > Pali Rohár writes: > > > On Wednesday 06 July 2022 12:43:08 Pali Rohár wrote: > > >> By default on PPC32 are PCI bus numbers unique across all PCI domains. > > >> So system could have only 256 PCI buses independently of available > > >> PCI domains. > > >> > > >> This is due to filling DT property pci-OF-bus-map which does not reflect > > >> multi-domain setup. > > >> > > >> On all powerpc platforms except chrp and powermac there is no DT property > > >> pci-OF-bus-map anymore and therefore it is possible on non-chrp/powermac > > >> platforms to avoid this limitation of maximal number of 256 PCI buses in > > >> system even on multi-domain setup. > > >> > > >> But avoiding this limitation would mean that all PCI and PCIe devices would > > >> be present on completely different BDF addresses as every PCI domain starts > > >> numbering PCI bueses from zero (instead of the last bus number of previous > > >> enumerated PCI domain). Such change could break existing software which > > >> expects fixed PCI bus numbers. > > >> > > >> So add a new config option CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT which > > >> enables this change. By default it is disabled. It cause that initial value > > >> of hose->first_busno is zero. > > >> > > >> Signed-off-by: Pali Rohár > > >> --- > > >> arch/powerpc/Kconfig | 11 +++++++++++ > > >> arch/powerpc/kernel/pci_32.c | 6 ++++++ > > >> 2 files changed, 17 insertions(+) > > >> > > >> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > > >> index be68c1f02b79..f66084bc1dfe 100644 > > >> --- a/arch/powerpc/Kconfig > > >> +++ b/arch/powerpc/Kconfig > > >> @@ -370,6 +370,17 @@ config PPC_DCR > > >> depends on PPC_DCR_NATIVE || PPC_DCR_MMIO > > >> default y > > >> > > >> +config PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT > > >> + depends on PPC32 > > >> + depends on !PPC_PMAC && !PPC_CHRP > > >> + bool "Assign PCI bus numbers from zero individually for each PCI domain" > > >> + help > > >> + By default on PPC32 were PCI bus numbers unique across all PCI domains. > > >> + So system could have only 256 PCI buses independently of available > > >> + PCI domains. When this option is enabled then PCI bus numbers are > > >> + PCI domain dependent and each PCI controller on own domain can have > > >> + 256 PCI buses, like it is on other Linux architectures. > > >> + > > > > > > What do you think, would it be possible to set default value of this > > > option to enabled? > > > > My preference would be to not have the option at all, just make it the > > default behaviour. Every new CONFIG option adds more combinations that > > need testing, or more likely don't get well tested. > > > > But I don't have a good feel for what could break if we turn it on, so > > honestly I don't really know. > > > > Also I do most of my 32-bit testing on pmacs, which are not affected by > > the change. > > It is because this change is incompatible with deprecated pci-OF-bus-map > which pmac uses. I do not have any pmac box for testing or development, > so I let this part as is. > > If one day pci-OF-bus-map would be possible to disable on pmac then this > pci bus number change can be enabled also for pmac. Hello! I have created this patch which allows to disable deprecated pci-OF-bus-map on powermac and allow to enable this new config option PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT also on powermac. So you can test this option too on your powermac boxes. I'm really not sure if that pci-OF-bus-map is required and for which platforms or software... Patch for allowing to disable pci-OF-bus-map is here: https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20220817163927.24453-1-pali@kernel.org/ > > So I'll probably take the series as-is, and then we can do some more > > widespread testing and possibly flip the default to enabled, and then > > maybe remove the option entirely in future. > > > > cheers > > I have tested it on P2020 board with 3 PCIe devices, each on own bus > where each bus is connected to different PCIe controller / domain and it > works correctly. Every PCIe device is on bus 1 bus but on different > domains.