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); 48