[PATCH v2 2/9] PCI: pciehp: Use RMW accessors for changing LNKCTL

From: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>
To: linux-pci@vger.kernel.org, "Bjorn Helgaas" <bhelgaas@google.com>,
	"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
	"Rob Herring" <robh@kernel.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Emmanuel Grumbach" <emmanuel.grumbach@intel.com>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	"Heiner Kallweit" <hkallweit1@gmail.com>,
	"Lukas Wunner" <lukas@wunner.de>,
	"Jesse Barnes" <jbarnes@virtuousgeek.org>,
	"Yinghai Lu" <yinghai@kernel.org>,
	linux-kernel@vger.kernel.org
Cc: "Dean Luick" <dean.luick@cornelisnetworks.com>,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>,
	stable@vger.kernel.org
Subject: [PATCH v2 2/9] PCI: pciehp: Use RMW accessors for changing LNKCTL
Date: Wed, 17 May 2023 13:52:28 +0300	[thread overview]
Message-ID: <20230517105235.29176-3-ilpo.jarvinen@linux.intel.com> (raw)
In-Reply-To: <20230517105235.29176-1-ilpo.jarvinen@linux.intel.com>

As hotplug is not the only driver touching LNKCTL, use the RMW
capability accessor which handles concurrent changes correctly.

Fixes: 7f822999e12a ("PCI: pciehp: Add Disable/enable link functions")
Suggested-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: stable@vger.kernel.org
---
 drivers/pci/hotplug/pciehp_hpc.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index f8c70115b691..26623e2884a3 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -332,17 +332,11 @@ int pciehp_check_link_status(struct controller *ctrl)
 static int __pciehp_link_set(struct controller *ctrl, bool enable)
 {
 	struct pci_dev *pdev = ctrl_dev(ctrl);
-	u16 lnk_ctrl;
 
-	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &lnk_ctrl);
+	pcie_capability_clear_and_set_word(pdev, PCI_EXP_LNKCTL,
+					   PCI_EXP_LNKCTL_LD,
+					   !enable ? PCI_EXP_LNKCTL_LD : 0);
 
-	if (enable)
-		lnk_ctrl &= ~PCI_EXP_LNKCTL_LD;
-	else
-		lnk_ctrl |= PCI_EXP_LNKCTL_LD;
-
-	pcie_capability_write_word(pdev, PCI_EXP_LNKCTL, lnk_ctrl);
-	ctrl_dbg(ctrl, "%s: lnk_ctrl = %x\n", __func__, lnk_ctrl);
 	return 0;
 }
 
-- 
2.30.2

