The KSZ8765 is similar to the KSZ8795 but has two fiber ports.
KSZ8_PORT_STATUS_0 is used to detect fiber mode. It is currently
defined as 0x08, which is the Global Control 6 MIB Control register
and has bit 7 defined as Flush Counter.
Set KSZ8_PORT_STATUS_0 to 0x18, which is the Port 1 Status 0 register
where bit 7 is the Fiber Mode bit.
This issue was discovered when upgrading an embedded device from kernel
5.10 to 6.16. The device was using a KSZ8765 device tree configuration
and the corresponding hardware, but during boot the kernel incorrectly
detected it as a KSZ8795. The relevant boot messages were:
ksz-switch spi0.0: found switch: KSZ8795, rev 0
ksz-switch spi0.0: Device tree specifies chip KSZ8765 but found KSZ8795, please fix it!
Cc: stable@vger.kernel.org
Fixes: 91a98917a8 ("net: dsa: microchip: move switch chip_id detection to ksz_common")
Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>
Signed-off-by: Sebastien Royen <sebastien.royen@armadeus.com>
Link: https://patch.msgid.link/20261007080557.15719-1-sebastien.royen@armadeus.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
fc13ba44da