linux-kernel - [PATCH v4 09/11] wifi: ath12k: Use RMW accessors for changing LNKCTL

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Message-Id: <20230713124505.94866-10-ilpo.jarvinen@linux.intel.com>
Date:   Thu, 13 Jul 2023 15:45:03 +0300
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Lukas Wunner <lukas@...ner.de>, Kalle Valo <kvalo@...nel.org>,
        P Praneesh <quic_ppranees@...cinc.com>,
        Sriram R <quic_srirrama@...cinc.com>,
        Carl Huang <quic_cjhuang@...cinc.com>,
        Bhagavathi Perumal S <quic_bperumal@...cinc.com>,
        ath12k@...ts.infradead.org, linux-wireless@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Dean Luick <dean.luick@...nelisnetworks.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Jonas Dreßler <verdre@...d.nl>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        Simon Horman <simon.horman@...igine.com>,
        stable@...r.kernel.org
Subject: [PATCH v4 09/11] wifi: ath12k: Use RMW accessors 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.

Use RMW capability accessors which do proper locking to avoid losing
concurrent updates to the register value. On restore, clear the ASPMC
field properly.

Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Suggested-by: Lukas Wunner <lukas@...ner.de>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Reviewed-by: Simon Horman <simon.horman@...igine.com>
Acked-by: Kalle Valo <kvalo@...nel.org>
Cc: stable@...r.kernel.org
---
 drivers/net/wireless/ath/ath12k/pci.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/ath/ath12k/pci.c b/drivers/net/wireless/ath/ath12k/pci.c
index 5990a55801f0..e4f08a066ca1 100644
--- a/drivers/net/wireless/ath/ath12k/pci.c
+++ b/drivers/net/wireless/ath/ath12k/pci.c
@@ -794,8 +794,8 @@ static void ath12k_pci_aspm_disable(struct ath12k_pci *ab_pci)
 		   u16_get_bits(ab_pci->link_ctl, PCI_EXP_LNKCTL_ASPM_L1));
 
 	/* disable L0s and L1 */
-	pcie_capability_write_word(ab_pci->pdev, PCI_EXP_LNKCTL,
-				   ab_pci->link_ctl & ~PCI_EXP_LNKCTL_ASPMC);
+	pcie_capability_clear_word(ab_pci->pdev, PCI_EXP_LNKCTL,
+				   PCI_EXP_LNKCTL_ASPMC);
 
 	set_bit(ATH12K_PCI_ASPM_RESTORE, &ab_pci->flags);
 }
@@ -803,8 +803,10 @@ static void ath12k_pci_aspm_disable(struct ath12k_pci *ab_pci)
 static void ath12k_pci_aspm_restore(struct ath12k_pci *ab_pci)
 {
 	if (test_and_clear_bit(ATH12K_PCI_ASPM_RESTORE, &ab_pci->flags))
-		pcie_capability_write_word(ab_pci->pdev, PCI_EXP_LNKCTL,
-					   ab_pci->link_ctl);
+		pcie_capability_clear_and_set_word(ab_pci->pdev, PCI_EXP_LNKCTL,
+						   PCI_EXP_LNKCTL_ASPMC,
+						   ab_pci->link_ctl &
+						   PCI_EXP_LNKCTL_ASPMC);
 }
 
 static void ath12k_pci_kill_tasklets(struct ath12k_base *ab)
-- 
2.30.2