linux-kernel - [PATCH 5.4 34/62] i2c: sprd: use a specific timeout to avoid system hang up issue

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Date:   Fri, 15 Jan 2021 13:27:56 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Linhua Xu <linhua.xu@...soc.com>,
        Chunyan Zhang <chunyan.zhang@...soc.com>,
        Wolfram Sang <wsa@...nel.org>
Subject: [PATCH 5.4 34/62] i2c: sprd: use a specific timeout to avoid system hang up issue

From: Chunyan Zhang <chunyan.zhang@...soc.com>

commit 0b884fe71f9ee6a5df35e677154256ea2099ebb8 upstream.

If the i2c device SCL bus being pulled up due to some exception before
message transfer done, the system cannot receive the completing interrupt
signal any more, it would not exit waiting loop until MAX_SCHEDULE_TIMEOUT
jiffies eclipse, that would make the system seemed hang up. To avoid that
happen, this patch adds a specific timeout for message transfer.

Fixes: 8b9ec0719834 ("i2c: Add Spreadtrum I2C controller driver")
Signed-off-by: Linhua Xu <linhua.xu@...soc.com>
Signed-off-by: Chunyan Zhang <chunyan.zhang@...soc.com>
[wsa: changed errno to ETIMEDOUT]
Signed-off-by: Wolfram Sang <wsa@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/i2c/busses/i2c-sprd.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/i2c/busses/i2c-sprd.c
+++ b/drivers/i2c/busses/i2c-sprd.c
@@ -72,6 +72,8 @@
 
 /* timeout (ms) for pm runtime autosuspend */
 #define SPRD_I2C_PM_TIMEOUT	1000
+/* timeout (ms) for transfer message */
+#define I2C_XFER_TIMEOUT	1000
 
 /* SPRD i2c data structure */
 struct sprd_i2c {
@@ -244,6 +246,7 @@ static int sprd_i2c_handle_msg(struct i2
 			       struct i2c_msg *msg, bool is_last_msg)
 {
 	struct sprd_i2c *i2c_dev = i2c_adap->algo_data;
+	unsigned long time_left;
 
 	i2c_dev->msg = msg;
 	i2c_dev->buf = msg->buf;
@@ -273,7 +276,10 @@ static int sprd_i2c_handle_msg(struct i2
 
 	sprd_i2c_opt_start(i2c_dev);
 
-	wait_for_completion(&i2c_dev->complete);
+	time_left = wait_for_completion_timeout(&i2c_dev->complete,
+				msecs_to_jiffies(I2C_XFER_TIMEOUT));
+	if (!time_left)
+		return -ETIMEDOUT;
 
 	return i2c_dev->err;
 }