6.12-stable review patch. If anyone has any objections, please let me know.
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From: Colin Foster colin.foster@in-advantage.com
[ Upstream commit 69777753a8919b0b8313c856e707e1d1fe5ced85 ]
When the EEPROM MAC is read by way of ADDRH, it can return all 0s the first time. Subsequent reads succeed.
This is fully reproduceable on the Phytec PCM049 SOM.
Re-read the ADDRH when this behaviour is observed, in an attempt to correctly apply the EEPROM MAC address.
Signed-off-by: Colin Foster colin.foster@in-advantage.com Link: https://patch.msgid.link/20250903132610.966787-1-colin.foster@in-advantage.c... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/smsc/smsc911x.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c index 74f1ccc964599..7e8cad0515e86 100644 --- a/drivers/net/ethernet/smsc/smsc911x.c +++ b/drivers/net/ethernet/smsc/smsc911x.c @@ -2163,10 +2163,20 @@ static const struct net_device_ops smsc911x_netdev_ops = { static void smsc911x_read_mac_address(struct net_device *dev) { struct smsc911x_data *pdata = netdev_priv(dev); - u32 mac_high16 = smsc911x_mac_read(pdata, ADDRH); - u32 mac_low32 = smsc911x_mac_read(pdata, ADDRL); + u32 mac_high16, mac_low32; u8 addr[ETH_ALEN];
+ mac_high16 = smsc911x_mac_read(pdata, ADDRH); + mac_low32 = smsc911x_mac_read(pdata, ADDRL); + + /* The first mac_read in some setups can incorrectly read 0. Re-read it + * to get the full MAC if this is observed. + */ + if (mac_high16 == 0) { + SMSC_TRACE(pdata, probe, "Re-read MAC ADDRH\n"); + mac_high16 = smsc911x_mac_read(pdata, ADDRH); + } + addr[0] = (u8)(mac_low32); addr[1] = (u8)(mac_low32 >> 8); addr[2] = (u8)(mac_low32 >> 16);