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.

Suggested-by: Lukas Wunner <lukas@wunner.de>
Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Link: https://lore.kernel.org/r/20230717120503.15276-10-ilpo.jarvinen@linux.intel.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Acked-by: Kalle Valo <kvalo@kernel.org>

diff --git a/drivers/net/wireless/ath/ath12k/pci.c b/drivers/net/wireless/ath/ath12k/pci.c
index 5990a55801f0a3991cb588d6c4de65e52228818f..e4f08a066ca10ab87d87baf80bed849e773846cf 100644 (file)
--- 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)