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

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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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