linux-kernel - [PATCH v2 01/10] PCI: Protect Link Control 2 Register with RMW locking

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Message-Id: <20230915120142.32987-2-ilpo.jarvinen@linux.intel.com>
Date:   Fri, 15 Sep 2023 15:01:33 +0300
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     linux-pci@...r.kernel.org, Bjorn Helgaas <helgaas@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Lukas Wunner <lukas@...ner.de>,
        Alexandru Gagniuc <mr.nuke.me@...il.com>,
        Krishna chaitanya chundru <quic_krichai@...cinc.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>, linux-pm@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Alex Deucher <alexdeucher@...il.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH v2 01/10] PCI: Protect Link Control 2 Register with RMW locking

PCIe Bandwidth Controller performs RMW accesses the Link Control 2
Register which can occur concurrently to other sources of Link Control
2 Register writes. Therefore, add Link Control 2 Register among the PCI
Express Capability Registers that need RMW locking.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---
 Documentation/PCI/pciebus-howto.rst | 8 ++++----
 include/linux/pci.h                 | 1 +
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/Documentation/PCI/pciebus-howto.rst b/Documentation/PCI/pciebus-howto.rst
index a0027e8fb0d0..3ba322ca1ce1 100644
--- a/Documentation/PCI/pciebus-howto.rst
+++ b/Documentation/PCI/pciebus-howto.rst
@@ -218,7 +218,7 @@ that is shared between many drivers including the service drivers.
 RMW Capability accessors (pcie_capability_clear_and_set_word(),
 pcie_capability_set_word(), and pcie_capability_clear_word()) protect
 a selected set of PCI Express Capability Registers (Link Control
-Register and Root Control Register). Any change to those registers
-should be performed using RMW accessors to avoid problems due to
-concurrent updates. For the up-to-date list of protected registers,
-see pcie_capability_clear_and_set_word().
+Register, Root Control Register, and Link Control 2 Register). Any
+change to those registers should be performed using RMW accessors to
+avoid problems due to concurrent updates. For the up-to-date list of
+protected registers, see pcie_capability_clear_and_set_word().
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 8c7c2c3c6c65..16db80f8b15c 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1243,6 +1243,7 @@ static inline int pcie_capability_clear_and_set_word(struct pci_dev *dev,
 {
 	switch (pos) {
 	case PCI_EXP_LNKCTL:
+	case PCI_EXP_LNKCTL2:
 	case PCI_EXP_RTCTL:
 		return pcie_capability_clear_and_set_word_locked(dev, pos,
 								 clear, set);
-- 
2.30.2