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SubjectRe: [PATCH 1/1] r8169: revert "read MAC address from EEPROM on init"
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[Reposting to lkml only, Gnus likes to eat quoting from email addresses
under specific circumstances and then vger doesn't pass them through]

Francois Romieu <romieu@fr.zoreil.com> writes:

> -static int rtl_eeprom_read(struct pci_dev *pdev, int cap, int addr, __le32 *val)
> -{
> - int ret, count = 100;
> - u16 status = 0;
> - u32 value;
> -
> - ret = pci_write_config_word(pdev, cap + PCI_VPD_ADDR, addr);
> - if (ret < 0)
> - return ret;
> -
> - do {
> - udelay(10);
> - ret = pci_read_config_word(pdev, cap + PCI_VPD_ADDR, &status);
> - if (ret < 0)
> - return ret;
> - } while (!(status & PCI_VPD_ADDR_F) && --count);
> -
> - if (!(status & PCI_VPD_ADDR_F))
> - return -ETIMEDOUT;
> -
> - ret = pci_read_config_dword(pdev, cap + PCI_VPD_DATA, &value);
> - if (ret < 0)
> - return ret;
> -
> - *val = cpu_to_le32(value);
> -
> - return 0;

Ahh, just PCI VPD.

IMHO the above shouldn't hurt anyone, in theory. You only write to
VPD_ADDR, and to change actual VPD data (i.e., EEPROM), you need to
write to VPD_DATA.

Anyone should be allowed to do that even for unknown PCI devices
without a problem.

> -static void rtl_init_mac_address(struct rtl8169_private *tp,

> - if (!(cfg1 & VPD)) {
> - if (netif_msg_probe(tp))
> - dev_info(&pdev->dev, "VPD access disabled, enabling\n");
> - RTL_W8(Cfg9346, Cfg9346_Unlock);
> - RTL_W8(Config1, cfg1 | VPD);
> - RTL_W8(Cfg9346, Cfg9346_Lock);

Now I wonder what do they say the above does exactly.
Unfortunately the docs don't seem to be public.

> - * MAC address is stored in EEPROM at offset 0x0e
> - * Realtek says: "The VPD address does not have to be a DWORD-aligned
> - * address as defined in the PCI 2.2 Specifications, but the VPD data
> - * is always consecutive 4-byte data starting from the VPD address
> - * specified."

Nice.

> - if (netif_msg_probe(tp)) {
> - DECLARE_MAC_BUF(buf);
> -
> - dev_info(&pdev->dev, "MAC address found in EEPROM: %s\n",
> - print_mac(buf, mac));
> - }
> -
> - if (is_valid_ether_addr(mac))
> - rtl_rar_set(tp, mac);
> -}

No RTL_W8(Config1, cfg1 | ~VPD) to disable (perhaps R/W) access?

Though obviously first reading a good address from the EEPROM and then
erasing first 32 bits is a different story. I wonder if changing the
MAC address by hand works (using ifconfig, to arbitrary address).

--
Krzysztof Halasa


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