drivers/net/wireless/mediatek/mt76/pci.c

   1 // SPDX-License-Identifier: ISC
   2 /*
   3  * Copyright (C) 2019 Lorenzo Bianconi <lorenzo@kernel.org>
   4  */
   5
   6 #include <linux/pci.h>
   7
   8 void mt76_pci_disable_aspm(struct pci_dev *pdev)
   9 {
  10         struct pci_dev *parent = pdev->bus->self;
  11         u16 aspm_conf, parent_aspm_conf = 0;
  12
  13         pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &aspm_conf);
  14         aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
  15         if (parent) {
  16                 pcie_capability_read_word(parent, PCI_EXP_LNKCTL,
  17                                           &parent_aspm_conf);
  18                 parent_aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
  19         }
  20
  21         if (!aspm_conf && (!parent || !parent_aspm_conf)) {
  22                 /* aspm already disabled */
  23                 return;
  24         }
  25
  26         dev_info(&pdev->dev, "disabling ASPM %s %s\n",
  27                  (aspm_conf & PCI_EXP_LNKCTL_ASPM_L0S) ? "L0s" : "",
  28                  (aspm_conf & PCI_EXP_LNKCTL_ASPM_L1) ? "L1" : "");
  29
  30         if (IS_ENABLED(CONFIG_PCIEASPM)) {
  31                 int err;
  32
  33                 err = pci_disable_link_state(pdev, aspm_conf);
  34                 if (!err)
  35                         return;
  36         }
  37
  38         /* both device and parent should have the same ASPM setting.
  39          * disable ASPM in downstream component first and then upstream.
  40          */
  41         pcie_capability_clear_word(pdev, PCI_EXP_LNKCTL, aspm_conf);
  42         if (parent)
  43                 pcie_capability_clear_word(parent, PCI_EXP_LNKCTL,
  44                                            aspm_conf);
  45 }
  46 EXPORT_SYMBOL_GPL(mt76_pci_disable_aspm);