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    SubjectRe: [PATCH -v2 1/3] PCI: introduce PCIe Device Serial Number Capability support
    On 07/11/2013 09:38 PM, Yijing Wang wrote:
    > Hi Don,
    > Thanks for your review and comments very much!
    >
    >>> + dev->sn = pci_device_serial_number(dev);
    >>> +
    >> Finally, 'the comment below':
    >> I know you were following Bjorn's suggestion, which I thought
    >> was an improvement, but why not do above assignment in pci_device_serial_number() ?
    >
    > I don't do assignment in pci_device_serial_number() because pci_device_serial_number()
    > is an EXPORT_SYMBOL, and will be used to get dsn for non-scaned device, for example:
    >
    > 1. we have pcie device in slot before suspend.
    > 2. we removed the device during suspend.
    > 3. we reinserted a new device during suspend.
    > 4. we should check the device change during resume, so we
    > try to use pcie device serial number to identify changes.
    > But the pci_dev structure maybe the old stale data. So
    > I prefer to get dsn by return.
    >
    > what about this:
    >
    > static void pci_init_capabilities(struct pci_dev *dev)
    > ........
    > pci_dsn_init(dev);
    > ..........
    >
    >
    > void pci_dsn_init(dev)
    > {
    > dev->sn = pci_device_serial_number(dev);
    > }
    >
    >
    >
    Looks good! I think that meets all the uses (use in init, post-suspend).
    - Don

    >> See above....
    >> - Don
    >>
    >>> /* Vital Product Data */
    >>> pci_vpd_pci22_init(dev);
    >>>
    >>> diff --git a/include/linux/pci.h b/include/linux/pci.h
    >>> index 0fd1f15..10d190b 100644
    >>> --- a/include/linux/pci.h
    >>> +++ b/include/linux/pci.h
    >>> @@ -342,6 +342,7 @@ struct pci_dev {
    >>> struct list_head msi_list;
    >>> struct kset *msi_kset;
    >>> #endif
    >>> + u64 sn; /* device serieal number, 0 if not support */
    >>> struct pci_vpd *vpd;
    >>> #ifdef CONFIG_PCI_ATS
    >>> union {
    >>> @@ -995,6 +996,8 @@ ssize_t pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf);
    >>> ssize_t pci_write_vpd(struct pci_dev *dev, loff_t pos, size_t count, const void *buf);
    >>> int pci_vpd_truncate(struct pci_dev *dev, size_t size);
    >>>
    >>> +u64 pci_device_serial_number(struct pci_dev *dev);
    >>> +
    >>> /* Helper functions for low-level code (drivers/pci/setup-[bus,res].c) */
    >>> resource_size_t pcibios_retrieve_fw_addr(struct pci_dev *dev, int idx);
    >>> void pci_bus_assign_resources(const struct pci_bus *bus);
    >>
    >>
    >> .
    >>
    >
    >



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