linux-kernel - [PATCH 10/17] mt76: Use pcie_lnkctl_clear_and

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Message-Id: <20230511131441.45704-11-ilpo.jarvinen@linux.intel.com>
Date:   Thu, 11 May 2023 16:14:34 +0300
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     linux-pci@...r.kernel.org, Bjorn Helgaas <helgaas@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Lukas Wunner <lukas@...ner.de>, Felix Fietkau <nbd@....name>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Ryder Lee <ryder.lee@...iatek.com>,
        Shayne Chen <shayne.chen@...iatek.com>,
        Sean Wang <sean.wang@...iatek.com>,
        Kalle Valo <kvalo@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Cc:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH 10/17] mt76: Use pcie_lnkctl_clear_and_set() for changing LNKCTL

Don't assume that only the driver would be accessing LNKCTL. ASPM
policy changes can trigger write to LNKCTL outside of driver's control.
And in the case of upstream (parent), the driver does not even own the
device it's changing LNKCTL for.

Use pcie_lnkctl_clear_and_set() which does proper locking to avoid
losing concurrent updates to the register value.

Suggested-by: Lukas Wunner <lukas@...ner.de>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---
 drivers/net/wireless/mediatek/mt76/pci.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/pci.c b/drivers/net/wireless/mediatek/mt76/pci.c
index 4c1c159fbb62..8c6444f5fac3 100644
--- a/drivers/net/wireless/mediatek/mt76/pci.c
+++ b/drivers/net/wireless/mediatek/mt76/pci.c
@@ -39,9 +39,8 @@ void mt76_pci_disable_aspm(struct pci_dev *pdev)
 	/* both device and parent should have the same ASPM setting.
 	 * disable ASPM in downstream component first and then upstream.
 	 */
-	pcie_capability_clear_word(pdev, PCI_EXP_LNKCTL, aspm_conf);
+	pcie_lnkctl_clear_and_set(pdev, aspm_conf, 0);
 	if (parent)
-		pcie_capability_clear_word(parent, PCI_EXP_LNKCTL,
-					   aspm_conf);
+		pcie_lnkctl_clear_and_set(parent, aspm_conf, 0);
 }
 EXPORT_SYMBOL_GPL(mt76_pci_disable_aspm);
-- 
2.30.2