RDMA/hns: Fix bug during CMDQ initialization

When reloading driver, the head/tail pointer of CMDQ may be not at
position 0. Then during initialization of CMDQ, if head is reset first,
the firmware will start to handle CMDQ because the head is not equal to
the tail. The driver can reset tail first since the firmware will be
triggerred only by head. This bug is introduced by changing macros of
head/tail register without changing the order of initialization.

Fixes: 292b335 ("RDMA/hns: Adjust fields and variables about CMDQ tail/head")
Link: https://lore.kernel.org/r/1615602611-7963-1-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

@@ -1194,8 +1194,10 @@ static void hns_roce_cmq_init_regs(struct hns_roce_dev *hr_dev, bool ring_type)
 			   upper_32_bits(dma));
 		roce_write(hr_dev, ROCEE_TX_CMQ_DEPTH_REG,
 			   (u32)ring->desc_num >> HNS_ROCE_CMQ_DESC_NUM_S);
-		roce_write(hr_dev, ROCEE_TX_CMQ_HEAD_REG, 0);
+
+		/* Make sure to write tail first and then head */
 		roce_write(hr_dev, ROCEE_TX_CMQ_TAIL_REG, 0);
+		roce_write(hr_dev, ROCEE_TX_CMQ_HEAD_REG, 0);
 	} else {
 		roce_write(hr_dev, ROCEE_RX_CMQ_BASEADDR_L_REG, (u32)dma);
 		roce_write(hr_dev, ROCEE_RX_CMQ_BASEADDR_H_REG,