PCI/VPD: Make missing VPD message less alarming

Realtek RTL8169/8168/8125 NIC families indicate VPD capability and an
optional VPD EEPROM can be connected via I2C/SPI. However I haven't seen
any card or system with such a VPD EEPROM yet. The missing EEPROM causes
the following warning whenever e.g. lscpi -vv is executed.

  invalid short VPD tag 00 at offset 01

The warning confuses users, and I think we should handle the situation more
gently. Therefore, if first VPD byte is read as 0x00, assume a missing
optional VPD PROM and replace the warning with a more descriptive message
at info level.

[bhelgaas: fix pre-existing whitespace]
Link: https://lore.kernel.org/r/ccbc11f1-4dbb-e2c8-d0ea-559e06d4c340@gmail.com


Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/vpd.c

@@ -71,10 +71,14 @@ static size_t pci_vpd_size(struct pci_dev *dev, size_t old_size)
 	size_t off = 0;
 	unsigned char header[1+2];	/* 1 byte tag, 2 bytes length */
 
-	while (off < old_size &&
-	       pci_read_vpd(dev, off, 1, header) == 1) {
+	while (off < old_size && pci_read_vpd(dev, off, 1, header) == 1) {
 		unsigned char tag;
 
+		if (!header[0] && !off) {
+			pci_info(dev, "Invalid VPD tag 00, assume missing optional VPD EPROM\n");
+			return 0;
+		}
+
 		if (header[0] & PCI_VPD_LRDT) {
 			/* Large Resource Data Type Tag */
 			tag = pci_vpd_lrdt_tag(header);