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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 B6C1AC1B0F2 for ; Wed, 20 Jun 2018 13:53:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 66CBC20836 for ; Wed, 20 Jun 2018 13:53:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 66CBC20836 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754468AbeFTNxw (ORCPT ); Wed, 20 Jun 2018 09:53:52 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:37568 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754446AbeFTNxu (ORCPT ); Wed, 20 Jun 2018 09:53:50 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id AB94D15B2; Wed, 20 Jun 2018 06:53:49 -0700 (PDT) Received: from big-swifty.cambridge.arm.com (big-swifty.cambridge.arm.com [10.1.31.224]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B657D3F578; Wed, 20 Jun 2018 06:53:44 -0700 (PDT) From: Marc Zyngier To: linux-kernel@vger.kernel.org Cc: Thomas Gleixner , Ard Biesheuvel , Shanker Donthineni , Shameer Kolothum , MaJun , Laurentiu Tudor , Lei Zhang Subject: [PATCH 7/7] irqchip/gic-v3-its: Reduce minimum LPI allocation to 1 for PCI devices Date: Wed, 20 Jun 2018 14:52:34 +0100 Message-Id: <20180620135234.32101-8-marc.zyngier@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180620135234.32101-1-marc.zyngier@arm.com> References: <20180620135234.32101-1-marc.zyngier@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Allocating a minimum of 32 LPIs per PCI device, let's reduce it to be just 1, as most devices do not need that many interrupts. We still have to special-case DevID 0, as there is plenty of broken HW around where the PCI RID is not presented as a DevID to the ITS, and all the devices are presented as DevID 0. In this case, we keep the 32 minimal allocation. Signed-off-by: Marc Zyngier --- drivers/irqchip/irq-gic-v3-its-pci-msi.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/irqchip/irq-gic-v3-its-pci-msi.c b/drivers/irqchip/irq-gic-v3-its-pci-msi.c index 75c3cafabc6a..8d6d009d1d58 100644 --- a/drivers/irqchip/irq-gic-v3-its-pci-msi.c +++ b/drivers/irqchip/irq-gic-v3-its-pci-msi.c @@ -66,7 +66,7 @@ static int its_pci_msi_prepare(struct irq_domain *domain, struct device *dev, { struct pci_dev *pdev, *alias_dev; struct msi_domain_info *msi_info; - int alias_count = 0; + int alias_count = 0, minnvec = 1; if (!dev_is_pci(dev)) return -EINVAL; @@ -86,9 +86,17 @@ static int its_pci_msi_prepare(struct irq_domain *domain, struct device *dev, /* ITS specific DeviceID, as the core ITS ignores dev. */ info->scratchpad[0].ul = pci_msi_domain_get_msi_rid(domain, pdev); - /* Allocate at least 32 MSIs, and always as a power of 2 */ + /* + * Always allocate a power of 2, and special case device 0 for + * broken systems where the DevID is not wired (and all devices + * appear as DevID 0). For that reason, we generously allocate a + * minimum of 32 MSIs for DevID 0. If you want more because all + * your devices are aliasing to DevID 0, consider fixing your HW. + */ nvec = max(nvec, alias_count); - nvec = max_t(int, 32, roundup_pow_of_two(nvec)); + if (!info->scratchpad[0].ul) + minnvec = 32; + nvec = max_t(int, minnvec, roundup_pow_of_two(nvec)); return msi_info->ops->msi_prepare(domain->parent, dev, nvec, info); } -- 2.17.1