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 "mt76.h"
   7 #include <linux/pci.h>
   8
   9 void mt76_pci_disable_aspm(struct pci_dev *pdev)
  10 {
  11         struct pci_dev *parent = pdev->bus->self;
  12         u16 aspm_conf, parent_aspm_conf = 0;
  13
  14         pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &aspm_conf);
  15         aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
  16         if (parent) {
  17                 pcie_capability_read_word(parent, PCI_EXP_LNKCTL,
  18                                           &parent_aspm_conf);
  19                 parent_aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
  20         }
  21
  22         if (!aspm_conf && (!parent || !parent_aspm_conf)) {
  23                 /* aspm already disabled */
  24                 return;
  25         }
  26
  27         dev_info(&pdev->dev, "disabling ASPM %s %s\n",
  28                  (aspm_conf & PCI_EXP_LNKCTL_ASPM_L0S) ? "L0s" : "",
  29                  (aspm_conf & PCI_EXP_LNKCTL_ASPM_L1) ? "L1" : "");
  30
  31         if (IS_ENABLED(CONFIG_PCIEASPM)) {
  32                 int err;
  33
  34                 err = pci_disable_link_state(pdev, aspm_conf);
  35                 if (!err)
  36                         return;
  37         }
  38
  39         /* both device and parent should have the same ASPM setting.
  40          * disable ASPM in downstream component first and then upstream.
  41          */
  42         pcie_capability_clear_word(pdev, PCI_EXP_LNKCTL, aspm_conf);
  43         if (parent)
  44                 pcie_capability_clear_word(parent, PCI_EXP_LNKCTL,
  45                                            aspm_conf);
  46 }
  47 EXPORT_SYMBOL_GPL(mt76_pci_disable_aspm);