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 B4B92C4332F for ; Wed, 12 Jan 2022 15:20:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238115AbiALPUc (ORCPT ); Wed, 12 Jan 2022 10:20:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59072 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354682AbiALPTQ (ORCPT ); Wed, 12 Jan 2022 10:19:16 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 50EFAC061212; Wed, 12 Jan 2022 07:19:06 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id 8FE756166E; Wed, 12 Jan 2022 15:19:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE727C36AEB; Wed, 12 Jan 2022 15:19:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1642000745; bh=fu0y6HF2w9TR9UC8AShHx0a+nQwyM62xkR4YrWTstSg=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=pG79wT9c/OQjU93VDoiJbr9aAubWS+bLRBbM3HIh+++enJ7Y6z9jc49LKf4f/IxHA pJgWvogXr42P86dH6qUACX7HC9f6/YfIfPuB0y//5G5Ue1rW8M0cYuue0Pgz2+KaMk EHSD0GG5AHUF6jxn3hqcfQ9tN1IVBJwPc5N70o/QhLcZG9gwfMGCDX3tvEHV5prJy/ urRoeo3WjwaYrm9mbgkuvRzY7+msPtGSoBImOo4V1cCc3SsvtyxZTRxKk+ibPl5OZk wzb68qRa+mezIUEEUr5CMj33kkvFcOHVZkDRcQrK9XG8rbDqywtapitODOaTxaOOaJ m9HvqXksWL6vw== Date: Wed, 12 Jan 2022 09:19:03 -0600 From: Bjorn Helgaas To: Jiaxun Yang Cc: Rob Herring , Lorenzo Pieralisi , Jonathan Hunter , Thierry Reding , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Tiezhu Yang , Huacai Chen , Ray Jui , Scott Branden , bcm-kernel-feedback-list@broadcom.com, linux-arm-kernel@lists.infradead.org, linux-pci , linux-tegra@vger.kernel.org Subject: Re: [PATCH 19/19] PCI: Set bridge map_irq and swizzle_irq to default functions Message-ID: <20220112151903.GA257550@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <013cc25a-d460-49eb-8cc0-8f59a0c5a45e@www.fastmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org On Wed, Jan 12, 2022 at 12:57:44PM +0000, Jiaxun Yang wrote: > 在2022年1月11日一月 下午9:46，Bjorn Helgaas写道： > > [-cc many, +cc iproc, loongson, tegra maintainers] > > > > On Tue, Jul 21, 2020 at 08:25:14PM -0600, Rob Herring wrote: > >> The majority of DT based host drivers use the default .map_irq() and > >> .swizzle_irq() functions, so let's initialize the function pointers to > >> the default and drop setting them in the host drivers. > >> > >> Drivers like iProc which don't support legacy interrupts need to set > >> .map_irq() back to NULL. > > > > Probably a dumb question... > > > > This patch removed all the ->swizzle_irq users in drivers/pci/, which > > is great -- IIUC swizzling is specified by the PCI-to-PCI Bridge Spec, > > r1.2, sec 9.1, and should not be device-specific. I assume the few > > remaining arch/ users (arm and alpha) are either bugs or workarounds > > for broken devices. > > > > My question is why we still have a few users of ->map_irq: loongson, > > tegra, iproc. Shouldn't this mapping be described somehow via DT? > > For Loongson we are describing IRQ map in DT for newer platforms. > But for legacy platforms (AMD RS780E North Bridge) with i8259 irqchip, > we need to read PCI IRQ registers to get mapping information. > > It is not known until boot time, so we have to use map_irq callback. I see these: Documentation/devicetree/bindings/pci/loongson.yaml arch/mips/boot/dts/loongson/rs780e-pch.dtsi which makes me think there are Loongson systems with DT. Are there some Loongson systems with DT and some legacy ones without? The only driver I see is drivers/pci/controller/pci-loongson.c. Is that used for all Loongson system? It unconditionally uses ->map_irq = loongson_map_irq(). loongson_map_irq() reads PCI_INTERRUPT_LINE; I think that depends on firmware having previously programmed it, right? Bjorn