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GET /api/patches/2216602/?format=api
{ "id": 2216602, "url": "http://patchwork.ozlabs.org/api/patches/2216602/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-pci/patch/20260326221311.1356180-1-bhelgaas@google.com/", "project": { "id": 28, "url": "http://patchwork.ozlabs.org/api/projects/28/?format=api", "name": "Linux PCI development", "link_name": "linux-pci", "list_id": "linux-pci.vger.kernel.org", "list_email": "linux-pci@vger.kernel.org", "web_url": null, "scm_url": null, "webscm_url": null, "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260326221311.1356180-1-bhelgaas@google.com>", "list_archive_url": null, "date": "2026-03-26T22:13:11", "name": "[v1] PCI: Remove MPS/MRRS Kconfig settings", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "8b95be44216d72c124e150211c2b7b462ef69c4c", "submitter": { "id": 67298, "url": "http://patchwork.ozlabs.org/api/people/67298/?format=api", "name": "Bjorn Helgaas", "email": "helgaas@kernel.org" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linux-pci/patch/20260326221311.1356180-1-bhelgaas@google.com/mbox/", "series": [ { "id": 497662, "url": "http://patchwork.ozlabs.org/api/series/497662/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-pci/list/?series=497662", "date": "2026-03-26T22:13:11", "name": "[v1] PCI: Remove MPS/MRRS Kconfig settings", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/497662/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2216602/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2216602/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <linux-pci+bounces-51240-incoming=patchwork.ozlabs.org@vger.kernel.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linux-pci@vger.kernel.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=LNNYwcvL;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c04:e001:36c::12fc:5321; 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a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;\n\tt=1774563216; cv=none;\n b=t2iXmVOQl2o+mlLsYajev6BWcXNj51WVVafPbQKpqzj3LAY6O5HUXUmlzsZG+CJZJoT520A4Mb9k+dvQ0oAWnSye7yTY4haNH/OKXQNrXMsxc6AyulGunKY6Yo1qIgH8zdEBc5ltbtLuHaHRAw4YYkUYt6Hk6lC/F1sBVFwZLD0=", "ARC-Message-Signature": "i=1; a=rsa-sha256; d=subspace.kernel.org;\n\ts=arc-20240116; t=1774563216; c=relaxed/simple;\n\tbh=BC2h89v1fE098rItLBk3R3hevS+LuWcLA/hkLEau6hY=;\n\th=From:To:Cc:Subject:Date:Message-ID:MIME-Version;\n b=Yab/di13KlA+MzphKzB2rWQTzRA+V6tPK7OhTYrLmemT4YVUPProXQYEKDb6QABV0R4VOMTdHzRmNlz9Lf3YSL2zS2A658pXEwdxx+MMXNaQdqHbQ2xNNwe3JNb/+rhM0TpfJ4FetbBw1lRWHY+T39SGx79pFPl15z2D+VbXab0=", "ARC-Authentication-Results": "i=1; smtp.subspace.kernel.org;\n dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org\n header.b=LNNYwcvL; arc=none smtp.client-ip=10.30.226.201", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;\n\ts=k20201202; t=1774563216;\n\tbh=BC2h89v1fE098rItLBk3R3hevS+LuWcLA/hkLEau6hY=;\n\th=From:To:Cc:Subject:Date:From;\n\tb=LNNYwcvLoDBf4pt2Bk8fiFkQ/uRMYE1dytl6K9OOmKnSjtUk7M039OVAJPAHpoNDG\n\t G/Nkvfhb3LEGaFWczqKbamiULtcazorHaaG2wWpzHB8iLSPttRjPPbuQFchCsa4tm6\n\t 8eeLSDi3CvfLWgD9ZgwIws+ii/3TwXoSvrr/SgB8znF9rkzk2kQk/1LmAHUusvnBUB\n\t 6R9Qt+gEhAPqrHXOOFKVMscXnAq1XwP/UC+KQ8akh5cxa3fwFjl9fVdaotzC8QejtA\n\t UzjY8PmO+TObv10LojKB7cn0mRGpxUTVEqGnsR8zsF21uMeJuSgo/UzA+ZclHGC8q8\n\t pJzwIkQkq+dcg==", "From": "Bjorn Helgaas <helgaas@kernel.org>", "To": "linux-pci@vger.kernel.org", "Cc": "Jim Quinlan <james.quinlan@broadcom.com>,\n\tFlorian Fainelli <florian.fainelli@broadcom.com>,\n\tHans Zhang <18255117159@163.com>,\n\tNiklas Cassel <cassel@kernel.org>,\n\tbcm-kernel-feedback-list@broadcom.com,\n\tlinux-kernel@vger.kernel.org,\n\tBjorn Helgaas <bhelgaas@google.com>", "Subject": "[PATCH v1] PCI: Remove MPS/MRRS Kconfig settings", "Date": "Thu, 26 Mar 2026 17:13:11 -0500", "Message-ID": "<20260326221311.1356180-1-bhelgaas@google.com>", "X-Mailer": "git-send-email 2.51.0", "Precedence": "bulk", "X-Mailing-List": "linux-pci@vger.kernel.org", "List-Id": "<linux-pci.vger.kernel.org>", "List-Subscribe": "<mailto:linux-pci+subscribe@vger.kernel.org>", "List-Unsubscribe": "<mailto:linux-pci+unsubscribe@vger.kernel.org>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit" }, "content": "This reverts b0e85c3c8554 (\"PCI: Add Kconfig options for MPS/MRRS\nstrategy\"), which allowed build-time selection of the \"off\", \"default\",\n\"safe\", \"performance\", or \"peer2peer\" strategies for MPS and MRRS\nconfiguration. These strategies can be selected at boot-time using the\n\"pci=pcie_bus_tune_*\" kernel parameters.\n\nPer the discussion mentioned below, these Kconfig options were added to\nwork around a hardware defect in a WiFi device used in a cable modem. The\ndefect occurred only when the device was configured with MPS=128, and\nKconfig was a way to avoid that setting. It was easier for the modem\nvendor to use Kconfig and update the kernel image than to change the kernel\nparameters.\n\nNeither Kconfig nor kernel parameters are a complete solution because the\nWiFi device may be used in other systems where it may be configured with\nMPS=128 and be susceptible to the defect.\n\nRemove the Kconfig settings to simplify the MPS code. If we can identify\nthe WiFi device in question, we may be able to make a generic quirk to\navoid the problem on all system.\n\nThis is not a fix and should not be backported to previous kernels.\n\nLink: https://lore.kernel.org/all/CA+-6iNzd0RJO0L021qz8CKrSviSst6QehY-QtJxz_-EVY0Hj0Q@mail.gmail.com\nSigned-off-by: Bjorn Helgaas <bhelgaas@google.com>\n---\n drivers/pci/Kconfig | 62 ---------------------------------------------\n drivers/pci/pci.c | 10 --------\n 2 files changed, 72 deletions(-)", "diff": "diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig\nindex e3f848ffb52a..f1330d219763 100644\n--- a/drivers/pci/Kconfig\n+++ b/drivers/pci/Kconfig\n@@ -252,68 +252,6 @@ config PCI_DYNAMIC_OF_NODES\n \t Once this option is selected, the device tree nodes will be generated\n \t for all PCI bridges.\n \n-choice\n-\tprompt \"PCI Express hierarchy optimization setting\"\n-\tdefault PCIE_BUS_DEFAULT\n-\tdepends on PCI && EXPERT\n-\thelp\n-\t MPS (Max Payload Size) and MRRS (Max Read Request Size) are PCIe\n-\t device parameters that affect performance and the ability to\n-\t support hotplug and peer-to-peer DMA.\n-\n-\t The following choices set the MPS and MRRS optimization strategy\n-\t at compile-time. The choices are the same as those offered for\n-\t the kernel command-line parameter 'pci', i.e.,\n-\t 'pci=pcie_bus_tune_off', 'pci=pcie_bus_safe',\n-\t 'pci=pcie_bus_perf', and 'pci=pcie_bus_peer2peer'.\n-\n-\t This is a compile-time setting and can be overridden by the above\n-\t command-line parameters. If unsure, choose PCIE_BUS_DEFAULT.\n-\n-config PCIE_BUS_TUNE_OFF\n-\tbool \"Tune Off\"\n-\tdepends on PCI\n-\thelp\n-\t Use the BIOS defaults; don't touch MPS at all. This is the same\n-\t as booting with 'pci=pcie_bus_tune_off'.\n-\n-config PCIE_BUS_DEFAULT\n-\tbool \"Default\"\n-\tdepends on PCI\n-\thelp\n-\t Default choice; ensure that the MPS matches upstream bridge.\n-\n-config PCIE_BUS_SAFE\n-\tbool \"Safe\"\n-\tdepends on PCI\n-\thelp\n-\t Use largest MPS that boot-time devices support. If you have a\n-\t closed system with no possibility of adding new devices, this\n-\t will use the largest MPS that's supported by all devices. This\n-\t is the same as booting with 'pci=pcie_bus_safe'.\n-\n-config PCIE_BUS_PERFORMANCE\n-\tbool \"Performance\"\n-\tdepends on PCI\n-\thelp\n-\t Use MPS and MRRS for best performance. Ensure that a given\n-\t device's MPS is no larger than its parent MPS, which allows us to\n-\t keep all switches/bridges to the max MPS supported by their\n-\t parent. This is the same as booting with 'pci=pcie_bus_perf'.\n-\n-config PCIE_BUS_PEER2PEER\n-\tbool \"Peer2peer\"\n-\tdepends on PCI\n-\thelp\n-\t Set MPS = 128 for all devices. MPS configuration effected by the\n-\t other options could cause the MPS on one root port to be\n-\t different than that of the MPS on another, which may cause\n-\t hot-added devices or peer-to-peer DMA to fail. Set MPS to the\n-\t smallest possible value (128B) system-wide to avoid these issues.\n-\t This is the same as booting with 'pci=pcie_bus_peer2peer'.\n-\n-endchoice\n-\n config VGA_ARB\n \tbool \"VGA Arbitration\" if EXPERT\n \tdefault y\ndiff --git a/drivers/pci/pci.c b/drivers/pci/pci.c\nindex 8479c2e1f74f..274c6685344e 100644\n--- a/drivers/pci/pci.c\n+++ b/drivers/pci/pci.c\n@@ -120,17 +120,7 @@ unsigned long pci_hotplug_bus_size = DEFAULT_HOTPLUG_BUS_SIZE;\n \n \n /* PCIe MPS/MRRS strategy; can be overridden by kernel command-line param */\n-#ifdef CONFIG_PCIE_BUS_TUNE_OFF\n-enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_TUNE_OFF;\n-#elif defined CONFIG_PCIE_BUS_SAFE\n-enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_SAFE;\n-#elif defined CONFIG_PCIE_BUS_PERFORMANCE\n-enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_PERFORMANCE;\n-#elif defined CONFIG_PCIE_BUS_PEER2PEER\n-enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_PEER2PEER;\n-#else\n enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_DEFAULT;\n-#endif\n \n /*\n * The default CLS is used if arch didn't set CLS explicitly and not\n", "prefixes": [ "v1" ] }