net: dsa: felix: fix tagging protocol changes with multiple CPU ports
When the device tree has 2 CPU ports defined, a single one is active (has any dp->cpu_dp pointers point to it). Yet the second one is still a CPU port, and DSA still calls ->change_tag_protocol on it. On the NXP LS1028A, the CPU ports are ports 4 and 5. Port 4 is the active CPU port and port 5 is inactive. After the following commands: # Initial setting cat /sys/class/net/eno2/dsa/tagging ocelot echo ocelot-8021q > /sys/class/net/eno2/dsa/tagging echo ocelot > /sys/class/net/eno2/dsa/tagging traffic is now broken, because the driver has moved the NPI port from port 4 to port 5, unbeknown to DSA. The problem can be avoided by detecting that the second CPU port is unused, and not doing anything for it. Further rework will be needed when proper support for multiple CPU ports is added. Treat this as a bug and prepare current kernels to work in single-CPU mode with multiple-CPU DT blobs. Fixes: adb3dccf ("net: dsa: felix: convert to the new .change_tag_protocol DSA API") Signed-off-by:Vladimir Oltean <vladimir.oltean@nxp.com> Link: https://lore.kernel.org/r/20220412172209.2531865-1-vladimir.oltean@nxp.com Signed-off-by:
Paolo Abeni <pabeni@redhat.com>
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