MLK-14241-1 regulator: pf1550-regulator-rpmsg: add mutex for pm_qos_add_request reentry

Multi drivers(mmc, cpufreq..) may access pf1550 regulator rpmsg driver at
the same time, so we have to add mutex for this multi-entry case. Otherwise
the below kernel warning maybe triggered:

------------[ cut here ]------------
WARNING: CPU: 0 PID: 19 at kernel/power/qos.c:453 pf1550_send_message+0x4c/0xf8()
pm_qos_add_request() called for already added request
Modules linked in:
CPU: 0 PID: 19 Comm: kworker/0:1 Not tainted 4.1.33-02293-g80b8c19 #636
Hardware name: Freescale i.MX7ULP (Device Tree)
Workqueue: events od_dbs_timer
[<80015d78>] (unwind_backtrace) from [<8001271c>] (show_stack+0x10/0x14)
[<8001271c>] (show_stack) from [<8082ba50>] (dump_stack+0x88/0x9c)
[<8082ba50>] (dump_stack) from [<800387c8>] (warn_slowpath_common+0x80/0xb0)
[<800387c8>] (warn_slowpath_common) from [<80038828>] (warn_slowpath_fmt+0x30/0x40)
[<80038828>] (warn_slowpath_fmt) from [<80341180>] (pf1550_send_message+0x4c/0xf8)
[<80341180>] (pf1550_send_message) from [<80341504>] (pf1550_get_voltage+0x48/0x5c)
[<80341504>] (pf1550_get_voltage) from [<803370a0>] (_regulator_get_voltage+0x68/0xb4)
[<803370a0>] (_regulator_get_voltage) from [<8033936c>] (_regulator_do_set_voltage+0x5c/0x3e4)
[<8033936c>] (_regulator_do_set_voltage) from [<803397a4>] (regulator_set_voltage+0xb0/0x14c)
[<803397a4>] (regulator_set_voltage) from [<8058dae8>] (imx7ulp_set_target+0x178/0x238)
[<8058dae8>] (imx7ulp_set_target) from [<80584d14>] (__cpufreq_driver_target+0x164/0x294)
[<80584d14>] (__cpufreq_driver_target) from [<8058bb08>] (dbs_check_cpu+0x1a0/0x1e0)
[<8058bb08>] (dbs_check_cpu) from [<805888e8>] (od_dbs_timer+0x80/0x138)
[<805888e8>] (od_dbs_timer) from [<8004bbbc>] (process_one_work+0x118/0x3e4)
[<8004bbbc>] (process_one_work) from [<8004bed4>] (worker_thread+0x4c/0x4f4)
[<8004bed4>] (worker_thread) from [<80050e4c>] (kthread+0xdc/0xf4)
[<80050e4c>] (kthread) from [<8000f528>] (ret_from_fork+0x14/0x2c)
---[ end trace f8281ecde7a0b4ce ]---
------------[ cut here ]------------

Signed-off-by: Robin Gong <yibin.gong@nxp.com>

1 files changed, 19 insertions, 11 deletions

diff --git a/drivers/regulator/pf1550-regulator-rpmsg.c b/drivers/regulator/pf1550-regulator-rpmsg.c
index 877dfa4dd6ed..57404ea95c68 100644
--- a/drivers/regulator/pf1550-regulator-rpmsg.c
+++ b/drivers/regulator/pf1550-regulator-rpmsg.c
@@ -74,6 +74,7 @@ struct pf1550_regulator_info {
 	struct pf1550_regulator_rpmsg *msg;
 	struct completion cmd_complete;
 	struct pm_qos_request pm_qos_req;
+	struct mutex lock;
 	struct regulator_desc *regulators;
 };
 
@@ -100,42 +101,47 @@ static int pf1550_send_message(struct pf1550_regulator_rpmsg *msg,
 {
 	int err;
 
-	msg->header.cate = IMX_RPMSG_PMIC;
-	msg->header.major = IMX_RMPSG_MAJOR;
-	msg->header.minor = IMX_RMPSG_MINOR;
-	msg->header.type = 0;
-
 	if (!info->rpdev) {
 		dev_dbg(info->dev,
 			 "rpmsg channel not ready, m4 image ready?\n");
 		return -EINVAL;
 	}
 
+	mutex_lock(&info->lock);
 	pm_qos_add_request(&info->pm_qos_req, PM_QOS_CPU_DMA_LATENCY, 0);
 
+	msg->header.cate = IMX_RPMSG_PMIC;
+	msg->header.major = IMX_RMPSG_MAJOR;
+	msg->header.minor = IMX_RMPSG_MINOR;
+	msg->header.type = 0;
+
 	/* wait response from rpmsg */
 	reinit_completion(&info->cmd_complete);
 
 	err = rpmsg_send(info->rpdev->ept, (void *)msg,
 			    sizeof(struct pf1550_regulator_rpmsg));
-
-	pm_qos_remove_request(&info->pm_qos_req);
-
 	if (err) {
 		dev_err(&info->rpdev->dev, "rpmsg_send failed: %d\n", err);
-		return err;
+		goto err_out;
 	}
 	err = wait_for_completion_timeout(&info->cmd_complete,
 					  msecs_to_jiffies(RPMSG_TIMEOUT));
 	if (!err) {
 		dev_err(&info->rpdev->dev, "rpmsg_send timeout!\n");
-		return -ETIMEDOUT;
+		err = -ETIMEDOUT;
+		goto err_out;
 	}
 
+	err = 0;
+
+err_out:
+	pm_qos_remove_request(&info->pm_qos_req);
+	mutex_unlock(&info->lock);
+
 	dev_dbg(&info->rpdev->dev, "cmd:%d, reg:%d, resp:%d.\n",
 		  msg->header.cmd, msg->regulator, msg->response);
 
-	return 0;
+	return err;
 }
 
 static int pf1550_enable(struct regulator_dev *reg)
@@ -327,6 +333,7 @@ static int rpmsg_regulator_probe(struct rpmsg_device *rpdev)
 	pf1550_info.rpdev = rpdev;
 
 	init_completion(&pf1550_info.cmd_complete);
+	mutex_init(&pf1550_info.lock);
 
 	dev_info(&rpdev->dev, "new channel: 0x%x -> 0x%x!\n",
 			rpdev->src, rpdev->dst);
@@ -469,6 +476,7 @@ static int pf1550_regulator_probe(struct platform_device *pdev)
 		return i;
 	}
 #endif
+
 	platform_set_drvdata(pdev, &pf1550_info);
 
 	return 0;