net: thunderx: Fix transmit queue timeout issue

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 <sgoutham@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 7 deletions

diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_queues.h b/drivers/net/ethernet/cavium/thunder/nicvf_queues.h
index 20511f2cb134..9e2104675bc9 100644
--- a/drivers/net/ethernet/cavium/thunder/nicvf_queues.h
+++ b/drivers/net/ethernet/cavium/thunder/nicvf_queues.h
@@ -88,13 +88,13 @@
 
 /* RED and Backpressure levels of CQ for pkt reception
  * For CQ, level is a measure of emptiness i.e 0x0 means full
- * eg: For CQ of size 4K, and for pass/drop levels of 128/96
- * HW accepts pkt if unused CQE >= 2048
- * RED accepts pkt if unused CQE < 2048 & >= 1536
- * DROPs pkts if unused CQE < 1536
+ * eg: For CQ of size 4K, and for pass/drop levels of 160/144
+ * HW accepts pkt if unused CQE >= 2560
+ * RED accepts pkt if unused CQE < 2304 & >= 2560
+ * DROPs pkts if unused CQE < 2304
  */
-#define RQ_PASS_CQ_LVL		128ULL
-#define RQ_DROP_CQ_LVL		96ULL
+#define RQ_PASS_CQ_LVL		160ULL
+#define RQ_DROP_CQ_LVL		144ULL
 
 /* RED and Backpressure levels of RBDR for pkt reception
  * For RBDR, level is a measure of fullness i.e 0x0 means empty
@@ -306,7 +306,8 @@ void nicvf_sq_disable(struct nicvf *nic, int qidx);
 void nicvf_put_sq_desc(struct snd_queue *sq, int desc_cnt);
 void nicvf_sq_free_used_descs(struct net_device *netdev,
 			      struct snd_queue *sq, int qidx);
-int nicvf_sq_append_skb(struct nicvf *nic, struct sk_buff *skb);
+int nicvf_sq_append_skb(struct nicvf *nic, struct snd_queue *sq,
+			struct sk_buff *skb, u8 sq_num);
 
 struct sk_buff *nicvf_get_rcv_skb(struct nicvf *nic, struct cqe_rx_t *cqe_rx);
 void nicvf_rbdr_task(unsigned long data);