Re: [PATCH -v2 1/3] PCI: introduce PCIe Device Serial Number Capabilitysupport

[Don Dutile]

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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