RDMA/hns: Optimize cmd init and mode selection for hip08

There are two modes for mailbox command (cmd) queue, i.e., event mode and
poll mode. For each mode, we use corresponding semaphores to protect the
cmd queue resource competition, so called event_sem and poll_sem. During
cmd init, both semaphores are initialized and poll mode is selected.
Thus, there is no need to up poll_sema again in cmd_use_polling.

Furthermore, there is no need to down the sema of the other side while
switching mode. This patch aims to decouple the switch between event mode
and poll mode of cmd.

Link: https://lore.kernel.org/r/1567068102-56919-2-git-send-email-liweihang@hisilicon.comSigned-off-by: Yixian Liu <liuyixian@huawei.com>
Signed-off-by: Weihang Li <liweihang@hisilicon.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/hns/hns_roce_cmd.c

@@ -251,23 +251,15 @@ int hns_roce_cmd_use_events(struct hns_roce_dev *hr_dev)
 	hr_cmd->token_mask = CMD_TOKEN_MASK;
 	hr_cmd->use_events = 1;
 
-	down(&hr_cmd->poll_sem);
-
 	return 0;
 }
 
 void hns_roce_cmd_use_polling(struct hns_roce_dev *hr_dev)
 {
 	struct hns_roce_cmdq *hr_cmd = &hr_dev->cmd;
-	int i;
-
-	hr_cmd->use_events = 0;
-
-	for (i = 0; i < hr_cmd->max_cmds; ++i)
-		down(&hr_cmd->event_sem);
 
 	kfree(hr_cmd->context);
-	up(&hr_cmd->poll_sem);
+	hr_cmd->use_events = 0;
 }
 
 struct hns_roce_cmd_mailbox

drivers/infiniband/hw/hns/hns_roce_main.c

@@ -902,6 +902,7 @@ int hns_roce_init(struct hns_roce_dev *hr_dev)
 		goto error_failed_cmd_init;
 	}
 
+	/* EQ depends on poll mode, event mode depends on EQ */
 	ret = hr_dev->hw->init_eq(hr_dev);
 	if (ret) {
 		dev_err(dev, "eq init failed!\n");
@@ -911,8 +912,9 @@ int hns_roce_init(struct hns_roce_dev *hr_dev)
 	if (hr_dev->cmd_mod) {
 		ret = hns_roce_cmd_use_events(hr_dev);
 		if (ret) {
-			dev_err(dev, "Switch to event-driven cmd failed!\n");
-			goto error_failed_use_event;
+			dev_warn(dev,
+				 "Cmd event  mode failed, set back to poll!\n");
+			hns_roce_cmd_use_polling(hr_dev);
 		}
 	}
 
@@ -955,8 +957,6 @@ int hns_roce_init(struct hns_roce_dev *hr_dev)
 error_failed_init_hem:
 	if (hr_dev->cmd_mod)
 		hns_roce_cmd_use_polling(hr_dev);
-
-error_failed_use_event:
 	hr_dev->hw->cleanup_eq(hr_dev);
 
 error_failed_eq_table: