[PATCH net v2 2/3] net: airoha: recover RX ring after hw completion stall

[Vitaliy Sochnev]

> IIUC increasing the ring size the issue never occurs again (correct?). If so, I
> would drop this patch for the moment and add it if it is really necessary.

Correct. At 128 the stall never occurred: 500 forced PPPoE reconnects
over 20 h, ~37500 samples, zero triggers, plus ~994 cycles in earlier
runs. This detector was compiled in and armed throughout, so that is a
measured absence, not just the absence of a visible symptom.

It is also not sufficient on its own: at 16 descriptors the recovery
fires roughly every 35 s and PPPoE still never completes, since each
recovery flushes the ring and negotiation restarts. The ring size is
what fixes the bug - and the other two patches on their own are what
ran the longest here: 508 forced reconnects over 20 h 32 min, zero
rx_dropped/rx_errors across 39158 samples.

Dropped in v3, just sent. I will resend this one with evidence if the
stall ever turns up at the larger ring.

Thanks for the review.

Vitaliy