From patchwork Thu Feb 25 15:10:22 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 12104397 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=-17.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 0EBD8C433DB for ; Thu, 25 Feb 2021 15:24:12 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 992DD64F17 for ; Thu, 25 Feb 2021 15:24:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 992DD64F17 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=zM9+3HXsK3BEkohAd1ozccZExAVkCjmWPr0AWqPnjws=; b=RtCHNZYBYsF2QPeEGe0g78Erl wCTmVZsm5+rkrPlf3s37IFI1mf2Foy3fxLhFUbwT13FoMCuF1pC4GSUIyQbPzXwFoZ88UpY5t+iUl 2QwjYomUx0/sEsisXxS5sH/nVzxmFg4sC437wIARfBqasbalBSgSYzxW9/UNP89jC5qLl/FkFgxh3 7OzPQBrQUT3q2KyLT/6Evoh/S7pjuTSf3VF3Z08gfHmUgy0A3PeO04hTCzg746EQKfPkAwo8Zq0zx U0x5mqNPR1crB0uA56m1HxJCqfbibAAHc6Y74MdZFl8LeTAiK/sWCLqxNqBnegFWGeXMRQMUH+6yO sTomfMZ7A==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1lFIUb-0007Vs-Ry; Thu, 25 Feb 2021 15:23:53 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1lFIUO-0007SW-Fj; Thu, 25 Feb 2021 15:23:42 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AD84864F11; Thu, 25 Feb 2021 15:23:39 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1lFIII-00Fscv-RS; Thu, 25 Feb 2021 15:11:11 +0000 From: Marc Zyngier To: Lorenzo Pieralisi , Bjorn Helgaas Subject: [PATCH 12/13] PCI: MSI: Document the various ways of ending up with NO_MSI Date: Thu, 25 Feb 2021 15:10:22 +0000 Message-Id: <20210225151023.3642391-13-maz@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210225151023.3642391-1-maz@kernel.org> References: <20210225151023.3642391-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: lorenzo.pieralisi@arm.com, bhelgaas@google.com, frank-w@public-files.de, treding@nvidia.com, tglx@linutronix.de, robh@kernel.org, will@kernel.org, kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, thierry.reding@gmail.com, jonathanh@nvidia.com, ryder.lee@mediatek.com, marek.vasut+renesas@gmail.com, yoshihiro.shimoda.uh@renesas.com, michal.simek@xilinx.com, paul.walmsley@sifive.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-hyperv@vger.kernel.org, linux-tegra@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-renesas-soc@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210225_102340_740520_6F27610E X-CRM114-Status: GOOD ( 14.71 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, Thierry Reding , "K. Y. Srinivasan" , Will Deacon , Marek Vasut , Rob Herring , Wei Liu , Ryder Lee , Stephen Hemminger , Michal Simek , Jonathan Hunter , Thierry Reding , Frank Wunderlich , Haiyang Zhang , linux-mediatek@lists.infradead.org, Paul Walmsley , linux-tegra@vger.kernel.org, Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Yoshihiro Shimoda , linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org We have now 4 ways of ending up with NO_MSI being set. Document them. Signed-off-by: Marc Zyngier --- drivers/pci/msi.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index d9c73c173c14..425abcdfcaca 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -871,8 +871,16 @@ static int pci_msi_supported(struct pci_dev *dev, int nvec) * Any bridge which does NOT route MSI transactions from its * secondary bus to its primary bus must set NO_MSI flag on * the secondary pci_bus. - * We expect only arch-specific PCI host bus controller driver - * or quirks for specific PCI bridges to be setting NO_MSI. + * + * The NO_MSI flag can either be set directly by: + * - arch-specific PCI host bus controller drivers (deprecated) + * - quirks for specific PCI bridges + * + * or indirectly by platform-specific PCI host bridge drivers by: + * - unconditionally advertising the 'no_msi' property + * - advertising the 'msi_domain' property, which results in + * the NO_MSI flag when no MSI domain is found for this bridge + * at probe time. */ for (bus = dev->bus; bus; bus = bus->parent) if (bus->bus_flags & PCI_BUS_FLAGS_NO_MSI)