Commit 029a6b3a14bf for kernel

commit 029a6b3a14bf02e6f59ce6ecd10f9d003334c612
Author: Maciej W. Rozycki <macro@orcam.me.uk>
Date:   Wed May 20 12:18:53 2026 +0100

    ethernet: 3c509: Fix AUI transceiver type selection

    The transceiver type is held in bits 15:14 of the Address Configuration
    Register, with the values of 0b00, 0b01, and 0b11 denoting TP, AUI, and
    BNC types respectively.  Therefore switching from BNC to AUI requires
    bits to be cleared before setting bit 14 or the setting won't change.

    NB this has always been wrong ever since this code was added in 2.5.42.

    Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
    Link: https://patch.msgid.link/alpine.DEB.2.21.2605201205160.1450@angie.orcam.me.uk
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/3com/3c509.c b/drivers/net/ethernet/3com/3c509.c
index fb68339e1511..67b9a3f4de5e 100644
--- a/drivers/net/ethernet/3com/3c509.c
+++ b/drivers/net/ethernet/3com/3c509.c
@@ -1099,6 +1099,7 @@ el3_netdev_set_ecmd(struct net_device *dev,
 		dev->if_port = 0;
 		break;
 	case PORT_AUI:
+		tmp &= ~(3<<14);
 		tmp |= (1<<14);
 		dev->if_port = 1;
 		break;