[PATCH net v3 0/2] net: airoha: fix silent RX loss on the shared CPU ring

[Vitaliy Sochnev]

v3: dropped the RX ring stall recovery (v2 2/3) as asked [1]. At 128 the
stall does not occur - 500 forced PPPoE reconnects over 20 h with the
detector compiled in and armed, zero triggers - and it did not fix the
bug on its own anyway. I will resend it if the stall turns up at the
larger ring.

2/2 keeps its code and its Acked-by; the commit message changed. It now
cites the register capture taken with no recovery in the tree instead of
numbers from builds carrying it, states that 1/2 does not cover this
failure, and quantifies what the bigger rings cost in memory.

v2 [2] answered the v1 review: DONE-bit overwrite hypothesis disproven,
QDMA_DESC_DROP_MASK never set, RX_DSCP_NUM default raised to the vendor
SDK's 32.

Still open for the airoha folks: in 2/2 hw set DONE on descriptor 15
while 0-14 were untouched and the driver's consumer sat at 0. Is
out-of-order completion within an RX ring expected, or is the driver
violating a constraint on RX_CPU_IDX by leaving one descriptor unposted?
Growing the ring avoids the symptom; the rule behind it is still unknown.

Tested on Nokia XG-040G-MF (AN7583) on a live PPPoE line. These two
patches without the recovery are what ran longest here: 508 forced
reconnects over 20 h 32 min, zero rx_dropped/rx_errors across 39158
samples.

[1] https://lore.kernel.org/netdev/apaA5jDYH71F0JaS@lore-desk/
[2] https://lore.kernel.org/netdev/20260831234701.206021-1-sochnev.v.74@gmail.com/

Vitaliy Sochnev (2):
  net: airoha: handle RX_NO_CPU_DSCP interrupt, not just RX_DONE
  net: airoha: grow the small RX rings

 drivers/net/ethernet/airoha/airoha_eth.c  | 16 +++++++++++-----
 drivers/net/ethernet/airoha/airoha_eth.h  |  3 ++-
 drivers/net/ethernet/airoha/airoha_regs.h |  2 ++
 3 files changed, 15 insertions(+), 6 deletions(-)

-- 
2.55.0