[PATCH net-next v2] net: thunderx: Fix transmit queue timeout issue

From: sunil.kovvuri@gmail.com
Date: Thu,  1 Dec 2016 18:24:28 +0530

From: Sunil Goutham <redacted>

Transmit queue timeout issue is seen in two cases
- Due to a race condition btw setting stop_queue at xmit()
  and checking for stopped_queue in NAPI poll routine, at times
  transmission from a SQ comes to a halt. This is fixed
  by using barriers and also added a check for SQ free descriptors,
  incase SQ is stopped and there are only CQE_RX i.e no CQE_TX.
- Contrary to an assumption, a HW errata where HW doesn't stop transmission
  even though there are not enough CQEs available for a CQE_TX is
  not fixed in T88 pass 2.x. This results in a Qset error with
  'CQ_WR_FULL' stalling transmission. This is fixed by adjusting
  RXQ's  RED levels for CQ level such that there is always enough
  space left for CQE_TXs.

Signed-off-by: Sunil Goutham <redacted>
---
v2: As suggested by David, replaced netif_tx_start_queue with 
    netif_tx_wake_queue.

Applied, thanks.