RDMA/hns: Remove redundant operations on CMDQ

CMDQ works serially, after each successful transmission, the head and tail
pointers will be equal, so there is no need to check whether the queue is
full. At the same time, since the descriptor of each transmission is new,
there is no need to perform a cleanup operation. Then, the field named
next_to_clean in structure hns_roce_v2_cmq_ring is redundant.

Fixes: a04ff73 ("RDMA/hns: Add command queue support for hip08 RoCE driver")
Link: https://lore.kernel.org/r/1612688143-28226-4-git-send-email-liweihang@huawei.com
Signed-off-by: Lang Cheng <chenglang@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/hns/hns_roce_hw_v2.c

@@ -1130,15 +1130,6 @@ static int hns_roce_v2_rst_process_cmd(struct hns_roce_dev *hr_dev)
 	return 0;
 }
 
-static int hns_roce_cmq_space(struct hns_roce_v2_cmq_ring *ring)
-{
-	int ntu = ring->next_to_use;
-	int ntc = ring->next_to_clean;
-	int used = (ntu - ntc + ring->desc_num) % ring->desc_num;
-
-	return ring->desc_num - used - 1;
-}
-
 static int hns_roce_alloc_cmq_desc(struct hns_roce_dev *hr_dev,
 				   struct hns_roce_v2_cmq_ring *ring)
 {
@@ -1178,7 +1169,6 @@ static int hns_roce_init_cmq_ring(struct hns_roce_dev *hr_dev, bool ring_type)
 					    &priv->cmq.csq : &priv->cmq.crq;
 
 	ring->flag = ring_type;
-	ring->next_to_clean = 0;
 	ring->next_to_use = 0;
 
 	return hns_roce_alloc_cmq_desc(hr_dev, ring);
@@ -1284,30 +1274,6 @@ static int hns_roce_cmq_csq_done(struct hns_roce_dev *hr_dev)
 	return head == priv->cmq.csq.next_to_use;
 }
 
-static int hns_roce_cmq_csq_clean(struct hns_roce_dev *hr_dev)
-{
-	struct hns_roce_v2_priv *priv = hr_dev->priv;
-	struct hns_roce_v2_cmq_ring *csq = &priv->cmq.csq;
-	struct hns_roce_cmq_desc *desc;
-	u16 ntc = csq->next_to_clean;
-	u32 head;
-	int clean = 0;
-
-	desc = &csq->desc[ntc];
-	head = roce_read(hr_dev, ROCEE_TX_CMQ_HEAD_REG);
-	while (head != ntc) {
-		memset(desc, 0, sizeof(*desc));
-		ntc++;
-		if (ntc == csq->desc_num)
-			ntc = 0;
-		desc = &csq->desc[ntc];
-		clean++;
-	}
-	csq->next_to_clean = ntc;
-
-	return clean;
-}
-
 static int __hns_roce_cmq_send(struct hns_roce_dev *hr_dev,
 			       struct hns_roce_cmq_desc *desc, int num)
 {
@@ -1322,15 +1288,6 @@ static int __hns_roce_cmq_send(struct hns_roce_dev *hr_dev,
 
 	spin_lock_bh(&csq->lock);
 
-	if (num > hns_roce_cmq_space(csq)) {
-		spin_unlock_bh(&csq->lock);
-		return -EBUSY;
-	}
-
-	/*
-	 * Record the location of desc in the cmq for this time
-	 * which will be use for hardware to write back
-	 */
 	ntc = csq->next_to_use;
 
 	while (handle < num) {
@@ -1377,15 +1334,14 @@ static int __hns_roce_cmq_send(struct hns_roce_dev *hr_dev,
 				ntc = 0;
 		}
 	} else {
+		/* FW/HW reset or incorrect number of desc */
+		ntc = roce_read(hr_dev, ROCEE_TX_CMQ_HEAD_REG);
+		dev_warn(hr_dev->dev, "CMDQ move head from %d to %d\n",
+			 csq->next_to_use, ntc);
+		csq->next_to_use = ntc;
 		ret = -EAGAIN;
 	}
 
-	/* clean the command send queue */
-	handle = hns_roce_cmq_csq_clean(hr_dev);
-	if (handle != num)
-		dev_warn(hr_dev->dev, "Cleaned %d, need to clean %d\n",
-			 handle, num);
-
 	spin_unlock_bh(&csq->lock);
 
 	return ret;

drivers/infiniband/hw/hns/hns_roce_hw_v2.h

@@ -1881,7 +1881,6 @@ struct hns_roce_v2_cmq_ring {
 	u16 buf_size;
 	u16 desc_num;
 	int next_to_use;
-	int next_to_clean;
 	u8 flag;
 	spinlock_t lock; /* command queue lock */
 };