From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757686Ab1JCVz6 (ORCPT ); Mon, 3 Oct 2011 17:55:58 -0400 Received: from mail-gy0-f174.google.com ([209.85.160.174]:50833 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757664Ab1JCVzx (ORCPT ); Mon, 3 Oct 2011 17:55:53 -0400 Date: Mon, 3 Oct 2011 16:55:48 -0500 From: Jon Mason To: Linus Torvalds Cc: Greg Kroah-Hartman , Jesse Barnes , Bjorn Helgaas , Benjamin Herrenschmidt , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Subject: [PATCH 2/3] pci: Clamp pcie_set_readrq() when using "performance" settings Message-ID: <20111003215547.GA3107@myri.com> References: <1317653420-21404-3-git-send-email-mason@myri.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1317653420-21404-3-git-send-email-mason@myri.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Benjamin Herrenschmidt When configuring the PCIe settings for "performance", we allow parents to have a larger Max Payload Size than children and rely on children Max Read Request Size to not be larger than their own MPS to avoid having the host bridge generate responses they can't cope with. However, various drivers in Linux call pci_set_readrq() with arbitrary values, assuming this to be a simple performance tweak. This breaks under our "performance" configuration. Fix that by making sure the value programmed by pcie_set_readrq() is never larger than the configured MPS for that device. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Jon Mason --- drivers/pci/pci.c | 18 ++++++++++++++++-- 1 files changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 4e84fd4..d369316 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3203,8 +3203,6 @@ int pcie_set_readrq(struct pci_dev *dev, int rq) if (rq < 128 || rq > 4096 || !is_power_of_2(rq)) goto out; - v = (ffs(rq) - 8) << 12; - cap = pci_pcie_cap(dev); if (!cap) goto out; @@ -3212,6 +3210,22 @@ int pcie_set_readrq(struct pci_dev *dev, int rq) err = pci_read_config_word(dev, cap + PCI_EXP_DEVCTL, &ctl); if (err) goto out; + /* + * If using the "performance" PCIe config, we clamp the + * read rq size to the max packet size to prevent the + * host bridge generating requests larger than we can + * cope with + */ + if (pcie_bus_config == PCIE_BUS_PERFORMANCE) { + int mps = pcie_get_mps(dev); + + if (mps < 0) + return mps; + if (mps < rq) + rq = mps; + } + + v = (ffs(rq) - 8) << 12; if ((ctl & PCI_EXP_DEVCTL_READRQ) != v) { ctl &= ~PCI_EXP_DEVCTL_READRQ; -- 1.7.6.2