cxgb4: Set VPD size so we can read both VPD structures

Chelsio adapters have two VPD structures stored in the VPD:

  - offset 0x000: an abbreviated VPD, and
  - offset 0x400: the complete VPD.

After 104daa71 ("PCI: Determine actual VPD size on first access"), the
PCI core computes the valid VPD size by parsing the VPD starting at offset
0x0.  That size only includes the abbreviated VPD structure, so reads of
the complete VPD at 0x400 fail.

Explicitly set the VPD size with pci_set_vpd_size() so the driver can read
both VPD structures.

[bhelgaas: changelog, split patches, rename to pci_set_vpd_size() and
return int (not ssize_t)]
Fixes: 104daa71 ("PCI: Determine actual VPD size on first access")
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/net/ethernet/chelsio/cxgb4/t4_hw.c

@@ -2557,6 +2557,7 @@ void t4_get_regs(struct adapter *adap, void *buf, size_t buf_size)
 }
 
 #define EEPROM_STAT_ADDR   0x7bfc
+#define VPD_SIZE           0x800
 #define VPD_BASE           0x400
 #define VPD_BASE_OLD       0
 #define VPD_LEN            1024
@@ -2594,6 +2595,15 @@ int t4_get_raw_vpd_params(struct adapter *adapter, struct vpd_params *p)
 	if (!vpd)
 		return -ENOMEM;
 
+	/* We have two VPD data structures stored in the adapter VPD area.
+	 * By default, Linux calculates the size of the VPD area by traversing
+	 * the first VPD area at offset 0x0, so we need to tell the OS what
+	 * our real VPD size is.
+	 */
+	ret = pci_set_vpd_size(adapter->pdev, VPD_SIZE);
+	if (ret < 0)
+		goto out;
+
 	/* Card information normally starts at VPD_BASE but early cards had
 	 * it at 0.
 	 */