[dpdk-dev] [PATCH 1/6] net/enic: enable RQ first and then post Rx buffers

[John Daley]

From: Hyong Youb Kim <hyon...@cisco.com>

Future VIC adapters may require that the driver enable RQ before
posting new buffers to the NIC. So split enic_alloc_rx_queue_mbufs()
into two functions, one that allocates buffers and fills RQ and the
other that posts them (i.e. PIO write to a doorbell). And, call the
post function only after enabling RQ.

Currently released models are not affected by this change, as they
work fine whether the driver posts buffers before or after enabling RQ.

Signed-off-by: Hyong Youb Kim <hyon...@cisco.com>
Reviewed-by: John Daley <johnd...@cisco.com>
Reviewed-by: Aaron Conole <acon...@redhat.com>
---
 drivers/net/enic/base/vnic_rq.h |  2 ++
 drivers/net/enic/enic_main.c    | 27 +++++++++++++++++++++++----
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/net/enic/base/vnic_rq.h b/drivers/net/enic/base/vnic_rq.h
index d774bb0db..9619290de 100644
--- a/drivers/net/enic/base/vnic_rq.h
+++ b/drivers/net/enic/base/vnic_rq.h
@@ -6,6 +6,7 @@
 #ifndef _VNIC_RQ_H_
 #define _VNIC_RQ_H_
 
+#include <stdbool.h>
 
 #include "vnic_dev.h"
 #include "vnic_cq.h"
@@ -69,6 +70,7 @@ struct vnic_rq {
        struct rte_mbuf *pkt_last_seg;
        unsigned int max_mbufs_per_pkt;
        uint16_t tot_nb_desc;
+       bool need_initial_post;
 };
 
 static inline unsigned int vnic_rq_desc_avail(struct vnic_rq *rq)
diff --git a/drivers/net/enic/enic_main.c b/drivers/net/enic/enic_main.c
index 2a2269794..e2adadcc9 100644
--- a/drivers/net/enic/enic_main.c
+++ b/drivers/net/enic/enic_main.c
@@ -315,6 +315,24 @@ enic_alloc_rx_queue_mbufs(struct enic *enic, struct 
vnic_rq *rq)
                                rq_buf_len);
                rq->mbuf_ring[i] = mb;
        }
+       /*
+        * Do not post the buffers to the NIC until we enable the RQ via
+        * enic_start_rq().
+        */
+       rq->need_initial_post = true;
+       return 0;
+}
+
+/*
+ * Post the Rx buffers for the first time. enic_alloc_rx_queue_mbufs() has
+ * allocated the buffers and filled the RQ descriptor ring. Just need to push
+ * the post index to the NIC.
+ */
+static void
+enic_initial_post_rx(struct enic *enic, struct vnic_rq *rq)
+{
+       if (!rq->in_use || !rq->need_initial_post)
+               return;
 
        /* make sure all prior writes are complete before doing the PIO write */
        rte_rmb();
@@ -329,9 +347,7 @@ enic_alloc_rx_queue_mbufs(struct enic *enic, struct vnic_rq 
*rq)
        iowrite32(rq->posted_index, &rq->ctrl->posted_index);
        iowrite32(0, &rq->ctrl->fetch_index);
        rte_rmb();
-
-       return 0;
-
+       rq->need_initial_post = false;
 }
 
 static void *
@@ -619,10 +635,13 @@ void enic_start_rq(struct enic *enic, uint16_t queue_idx)
        rq_data = &enic->rq[rq_sop->data_queue_idx];
        struct rte_eth_dev *eth_dev = enic->rte_dev;
 
-       if (rq_data->in_use)
+       if (rq_data->in_use) {
                vnic_rq_enable(rq_data);
+               enic_initial_post_rx(enic, rq_data);
+       }
        rte_mb();
        vnic_rq_enable(rq_sop);
+       enic_initial_post_rx(enic, rq_sop);
        eth_dev->data->rx_queue_state[queue_idx] = RTE_ETH_QUEUE_STATE_STARTED;
 }
 
-- 
2.16.2