From patchwork Mon Mar 22 18:46:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 12155891 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=-17.2 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 38717C433C1 for ; Mon, 22 Mar 2021 18:55:47 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 7C66D61992 for ; Mon, 22 Mar 2021 18:55:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7C66D61992 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-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:Cc:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=G5HJCwPLvM223Dax13kJBdtwHkX2f28mbWG1YIZrRUQ=; b=d28WN/vFgLOSnMdDa4PULVIi8 FY4f6JYxzBH7RUDI87uYDB1nZqTUTf9hBs4XvcImiLpgeIUS/QysVTKpIi56a17mVhYM5UsH34/Kq A9G1jvlEdvp+F817xlofBZ77QysbLil2W//hegs9Xi8X6vy0rIZNz7uwUs0BY5MwTxQG5chKjeiTc JE/7myDioD8yIdg7YFVrRhfar7rTnlJzQ9/0yPVgT3TzI1UgV6Ta2AdL2RgZiy4/Ou8WrSvt7eFef qAQti3ISvM+fQIaFmF5wVNGLxqUf5dS1URhUss1bdvKLkBr9iax0gFnU3KkjP7h5G7N091IZgnTSk o4F4wvqZA==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lOPgQ-00CKtn-Nq; Mon, 22 Mar 2021 18:53:46 +0000 Received: from mail.kernel.org ([198.145.29.99]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lOPgJ-00CKrS-Jw; Mon, 22 Mar 2021 18:53:43 +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 1A77361992; Mon, 22 Mar 2021 18:53:38 +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 1lOPZU-0038p5-VF; Mon, 22 Mar 2021 18:46:37 +0000 From: Marc Zyngier To: Lorenzo Pieralisi , Bjorn Helgaas Cc: Frank Wunderlich , Thierry Reding , Thomas Gleixner , Rob Herring , Will Deacon , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Michael Kelley , Wei Liu , Thierry Reding , Jonathan Hunter , Ryder Lee , Marek Vasut , Yoshihiro Shimoda , Michal Simek , Paul Walmsley , 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, kernel-team@android.com Subject: [PATCH v2 14/15] PCI/MSI: Document the various ways of ending up with NO_MSI Date: Mon, 22 Mar 2021 18:46:13 +0000 Message-Id: <20210322184614.802565-15-maz@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210322184614.802565-1-maz@kernel.org> References: <20210322184614.802565-1-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, mikelley@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, kernel-team@android.com 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-20210322_185340_053055_4D27DB11 X-CRM114-Status: GOOD ( 14.18 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org We have now 4 ways of ending up with NO_MSI being set. Document them. Acked-by: Bjorn Helgaas 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)