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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,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 4866FC49361 for ; Mon, 28 Jun 2021 10:12:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3367361982 for ; Mon, 28 Jun 2021 10:12:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232348AbhF1KPG (ORCPT ); Mon, 28 Jun 2021 06:15:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:51248 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232802AbhF1KOi (ORCPT ); Mon, 28 Jun 2021 06:14:38 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1EA2E61982; Mon, 28 Jun 2021 10:12:10 +0000 (UTC) From: Huacai Chen To: Bjorn Helgaas Cc: linux-pci@vger.kernel.org, Xuefeng Li , Huacai Chen , Jiaxun Yang , Huacai Chen Subject: [PATCH V4 3/4] PCI: Improve the MRRS quirk for LS7A Date: Mon, 28 Jun 2021 18:10:26 +0800 Message-Id: <20210628101027.1372370-4-chenhuacai@loongson.cn> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210628101027.1372370-1-chenhuacai@loongson.cn> References: <20210628101027.1372370-1-chenhuacai@loongson.cn> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org In new revision of LS7A, some PCIe ports support larger value than 256, but their maximum supported MRRS values are not detectable. Moreover, the current loongson_mrrs_quirk() cannot avoid devices increasing its MRRS after pci_enable_device(), and some devices (e.g. Realtek 8169) will actually set a big value in its driver. So the only possible way is configure MRRS of all devices in BIOS, and add a PCI bus flag (i.e., PCI_BUS_FLAGS_NO_INC_MRRS) to stop the increasing MRRS operations. However, according to PCIe Spec, it is legal for an OS to program any value for MRRS, and it is also legal for an endpoint to generate a Read Request with any size up to its MRRS. As the hardware engineers say, the root cause here is LS7A doesn't break up large read requests. In detail, LS7A PCIe port reports CA (Completer Abort) if it receives a Memory Read request with a size that's "too big" (Yes, that is a problem in the LS7A hardware design). Signed-off-by: Huacai Chen --- drivers/pci/pci.c | 5 +++++ drivers/pci/quirks.c | 41 +++++++++++------------------------------ include/linux/pci.h | 1 + 3 files changed, 17 insertions(+), 30 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 8d4ebe095d0c..0f1ff4a6fe44 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5812,6 +5812,11 @@ int pcie_set_readrq(struct pci_dev *dev, int rq) v = (ffs(rq) - 8) << 12; + if (dev->bus->bus_flags & PCI_BUS_FLAGS_NO_INC_MRRS) { + if (rq > pcie_get_readrq(dev)) + return -EINVAL; + } + ret = pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_DEVCTL_READRQ, v); diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index dee4798a49fc..4bbdf5a5425f 100644 --- a/drivers/pci/quirks.c +++ b/drivers/pci/quirks.c @@ -242,37 +242,18 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON, DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON, DEV_LS7A_LPC, loongson_system_bus_quirk); -static void loongson_mrrs_quirk(struct pci_dev *dev) -{ - struct pci_bus *bus = dev->bus; - struct pci_dev *bridge; - static const struct pci_device_id bridge_devids[] = { - { PCI_VDEVICE(LOONGSON, DEV_PCIE_PORT_0) }, - { PCI_VDEVICE(LOONGSON, DEV_PCIE_PORT_1) }, - { PCI_VDEVICE(LOONGSON, DEV_PCIE_PORT_2) }, - { 0, }, - }; - - /* look for the matching bridge */ - while (!pci_is_root_bus(bus)) { - bridge = bus->self; - bus = bus->parent; - /* - * Some Loongson PCIe ports have a h/w limitation of - * 256 bytes maximum read request size. They can't handle - * anything larger than this. So force this limit on - * any devices attached under these ports. - */ - if (pci_match_id(bridge_devids, bridge)) { - if (pcie_get_readrq(dev) > 256) { - pci_info(dev, "limiting MRRS to 256\n"); - pcie_set_readrq(dev, 256); - } - break; - } - } +static void loongson_mrrs_quirk(struct pci_dev *pdev) +{ + /* + * Some Loongson PCIe ports have h/w limitations of maximum read + * request size. They can't handle anything larger than this. So + * force this limit on any devices attached under these ports. + */ + pdev->subordinate->bus_flags |= PCI_BUS_FLAGS_NO_INC_MRRS; } -DECLARE_PCI_FIXUP_ENABLE(PCI_ANY_ID, PCI_ANY_ID, loongson_mrrs_quirk); +DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_LOONGSON, DEV_PCIE_PORT_0, loongson_mrrs_quirk); +DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_LOONGSON, DEV_PCIE_PORT_1, loongson_mrrs_quirk); +DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_LOONGSON, DEV_PCIE_PORT_2, loongson_mrrs_quirk); /* * The Mellanox Tavor device gives false positive parity errors. Disable diff --git a/include/linux/pci.h b/include/linux/pci.h index 24306504226a..b336239b5282 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -240,6 +240,7 @@ enum pci_bus_flags { PCI_BUS_FLAGS_NO_MMRBC = (__force pci_bus_flags_t) 2, PCI_BUS_FLAGS_NO_AERSID = (__force pci_bus_flags_t) 4, PCI_BUS_FLAGS_NO_EXTCFG = (__force pci_bus_flags_t) 8, + PCI_BUS_FLAGS_NO_INC_MRRS = (__force pci_bus_flags_t) 16, }; /* Values from Link Status register, PCIe r3.1, sec 7.8.8 */ -- 2.27.0