| 1 | // SPDX-License-Identifier: ISC |
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| 2 | /* |
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| 3 | * Copyright (C) 2019 Lorenzo Bianconi <lorenzo@kernel.org> |
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| 4 | */ |
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| 5 | |
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| 6 | #include "mt76.h" |
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| 7 | #include <linux/pci.h> |
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| 8 | |
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| 9 | void mt76_pci_disable_aspm(struct pci_dev *pdev) |
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| 10 | { |
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| 11 | struct pci_dev *parent = pdev->bus->self; |
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| 12 | u16 aspm_conf, parent_aspm_conf = 0; |
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| 13 | |
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| 14 | pcie_capability_read_word(dev: pdev, PCI_EXP_LNKCTL, val: &aspm_conf); |
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| 15 | aspm_conf &= PCI_EXP_LNKCTL_ASPMC; |
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| 16 | if (parent) { |
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| 17 | pcie_capability_read_word(dev: parent, PCI_EXP_LNKCTL, |
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| 18 | val: &parent_aspm_conf); |
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| 19 | parent_aspm_conf &= PCI_EXP_LNKCTL_ASPMC; |
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| 20 | } |
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| 21 | |
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| 22 | if (!aspm_conf && (!parent || !parent_aspm_conf)) { |
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| 23 | /* aspm already disabled */ |
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| 24 | return; |
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| 25 | } |
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| 26 | |
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| 27 | dev_info(&pdev->dev, "disabling ASPM %s %s\n" , |
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| 28 | (aspm_conf & PCI_EXP_LNKCTL_ASPM_L0S) ? "L0s" : "" , |
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| 29 | (aspm_conf & PCI_EXP_LNKCTL_ASPM_L1) ? "L1" : "" ); |
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| 30 | |
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| 31 | if (IS_ENABLED(CONFIG_PCIEASPM)) { |
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| 32 | int err; |
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| 33 | |
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| 34 | err = pci_disable_link_state(pdev, state: aspm_conf); |
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| 35 | if (!err) |
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| 36 | return; |
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| 37 | } |
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| 38 | |
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| 39 | /* both device and parent should have the same ASPM setting. |
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| 40 | * disable ASPM in downstream component first and then upstream. |
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| 41 | */ |
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| 42 | pcie_capability_clear_word(dev: pdev, PCI_EXP_LNKCTL, clear: aspm_conf); |
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| 43 | if (parent) |
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| 44 | pcie_capability_clear_word(dev: parent, PCI_EXP_LNKCTL, |
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| 45 | clear: aspm_conf); |
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| 46 | } |
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| 47 | EXPORT_SYMBOL_GPL(mt76_pci_disable_aspm); |
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| 48 | |
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