wait_for_completion_timeout() returns unsigned long not int.
It returns 0 if timed out, and positive if completed.
The check for < 0 is ambiguous and should be == 0 here
indicating timeout which is the only error case.

Fixes: 389711b37493 ("firmware: Add Turris Mox rWTM firmware driver")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
---
 drivers/firmware/turris-mox-rwtm.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/firmware/turris-mox-rwtm.c b/drivers/firmware/turris-mox-rwtm.c
index c2d34dc8ba46..2090afe00b7f 100644
--- a/drivers/firmware/turris-mox-rwtm.c
+++ b/drivers/firmware/turris-mox-rwtm.c
@@ -193,15 +193,16 @@ static int mox_get_board_info(struct mox_rwtm *rwtm)
 	struct armada_37xx_rwtm_tx_msg msg;
 	struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
 	int ret;
+	unsigned long time_left;
 
 	msg.command = MBOX_CMD_BOARD_INFO;
 	ret = mbox_send_message(rwtm->mbox, &msg);
 	if (ret < 0)
 		return ret;
 
-	ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
-	if (ret < 0)
-		return ret;
+	time_left = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
+	if (time_left == 0)
+		return -ETIMEDOUT;
 
 	ret = mox_get_status(MBOX_CMD_BOARD_INFO, reply->retval);
 	if (ret == -ENODATA) {
@@ -235,9 +236,9 @@ static int mox_get_board_info(struct mox_rwtm *rwtm)
 	if (ret < 0)
 		return ret;
 
-	ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
-	if (ret < 0)
-		return ret;
+	time_left = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
+	if (time_left == 0)
+		return -ETIMEDOUT;
 
 	ret = mox_get_status(MBOX_CMD_ECDSA_PUB_KEY, reply->retval);
 	if (ret == -ENODATA) {
@@ -264,6 +265,7 @@ static int check_get_random_support(struct mox_rwtm *rwtm)
 {
 	struct armada_37xx_rwtm_tx_msg msg;
 	int ret;
+	unsigned long time_left;
 
 	msg.command = MBOX_CMD_GET_RANDOM;
 	msg.args[0] = 1;
@@ -274,9 +276,9 @@ static int check_get_random_support(struct mox_rwtm *rwtm)
 	if (ret < 0)
 		return ret;
 
-	ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
-	if (ret < 0)
-		return ret;
+	time_left = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
+	if (time_left == 0)
+		return -ETIMEDOUT;
 
 	return mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
 }
-- 
2.17.1