[PATCH v2] i2c: sprd: use a specific timeout to avoid system hang up issue

[PATCH v2] i2c: sprd: use a specific timeout to avoid system hang up issue

[Chunyan Zhang]

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

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@unisoc.com>
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
---
* Changes since v1:
- Addressed Wolfram's comments for code;
- Changed to use Signed-off-by instead of Original-by;
- Fixed a compile error.
---
 drivers/i2c/busses/i2c-sprd.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-sprd.c b/drivers/i2c/busses/i2c-sprd.c
index 19cda6742423..b9f58a4b2281 100644
--- 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 i2c_adapter *i2c_adap,
 			       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 i2c_adapter *i2c_adap,
 
 	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 -EIO;
 
 	return i2c_dev->err;
 }
-- 
2.25.1

Re: [PATCH v2] i2c: sprd: use a specific timeout to avoid system hang up issue

[Wolfram Sang]

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On Mon, Dec 14, 2020 at 12:58:50PM +0800, Chunyan Zhang wrote:
> From: Chunyan Zhang <chunyan.zhang@unisoc.com>
> 
> 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@unisoc.com>
> Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>

Took the liberty to change the errno to ETIMEDOUT and applied to
for-current, thanks!


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Re: [PATCH v2] i2c: sprd: use a specific timeout to avoid system hang up issue

[Chunyan Zhang]

On Tue, 5 Jan 2021 at 02:24, Wolfram Sang <wsa@kernel.org> wrote:
>
> On Mon, Dec 14, 2020 at 12:58:50PM +0800, Chunyan Zhang wrote:
> > From: Chunyan Zhang <chunyan.zhang@unisoc.com>
> >
> > 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@unisoc.com>
> > Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
>
> Took the liberty to change the errno to ETIMEDOUT and applied to
> for-current, thanks!

Thanks!

Chunyan

>