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    SubjectRe: [RFC PATCH v2] PCI/portdrv: Only disable Bus Master on kexec reboot and connected PCI devices
    On Mon, Sep 14, 2020 at 04:29:10AM +0800, Tiezhu Yang wrote:
    > --- a/drivers/pci/pcie/portdrv_pci.c
    > +++ b/drivers/pci/pcie/portdrv_pci.c
    > @@ -143,6 +144,28 @@ static void pcie_portdrv_remove(struct pci_dev *dev)
    > }
    >
    > pcie_port_device_remove(dev);
    > + pci_disable_device(dev);
    > +}
    > +
    > +static void pcie_portdrv_shutdown(struct pci_dev *dev)
    > +{
    > + if (pci_bridge_d3_possible(dev)) {
    > + pm_runtime_forbid(&dev->dev);
    > + pm_runtime_get_noresume(&dev->dev);
    > + pm_runtime_dont_use_autosuspend(&dev->dev);
    > + }
    > +
    > + pcie_port_device_remove(dev);
    > +
    > + /*
    > + * If this is a kexec reboot, turn off Bus Master bit on the
    > + * device to tell it to not continue to do DMA. Don't touch
    > + * devices in D3cold or unknown states.
    > + * If it is not a kexec reboot, firmware will hit the PCI
    > + * devices with big hammer and stop their DMA any way.
    > + */
    > + if (kexec_in_progress && (dev->current_state <= PCI_D3hot))
    > + pci_disable_device(dev);

    The last portion of this function is already executed afterwards by
    pci_device_shutdown(). You don't need to duplicate it here:

    device_shutdown()
    dev->bus->shutdown() == pci_device_shutdown()
    drv->shutdown() == pcie_portdrv_shutdown()
    pci_disable_device()
    pci_disable_device()

    Thanks,

    Lukas

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