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authorVille Syrjala <syrjala@sci.fi>2012-03-15 18:11:05 +0100
committerJean Delvare <khali@endymion.delvare>2012-03-15 18:11:05 +0100
commit8ee161ce5e0cfc689eb677f227a6248191165fac (patch)
treee1c6aa2b4788eec7e9e552b90be10cd4ae5333ef
parent834aa6f30c2f5f5ab7c858e37800c1a19dfde2fb (diff)
downloadlinux-sh-8ee161ce5e0cfc689eb677f227a6248191165fac.tar.gz
i2c-algo-bit: Fix spurious SCL timeouts under heavy load
When the system is under heavy load, there can be a significant delay between the getscl() and time_after() calls inside sclhi(). That delay may cause the time_after() check to trigger after SCL has gone high, causing sclhi() to return -ETIMEDOUT. To fix the problem, double check that SCL is still low after the timeout has been reached, before deciding to return -ETIMEDOUT. Signed-off-by: Ville Syrjala <syrjala@sci.fi> Cc: stable@vger.kernel.org Signed-off-by: Jean Delvare <khali@linux-fr.org>
-rw-r--r--drivers/i2c/algos/i2c-algo-bit.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index 525c7345fa0b..24f94f4ae395 100644
--- a/drivers/i2c/algos/i2c-algo-bit.c
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -103,8 +103,14 @@ static int sclhi(struct i2c_algo_bit_data *adap)
* chips may hold it low ("clock stretching") while they
* are processing data internally.
*/
- if (time_after(jiffies, start + adap->timeout))
+ if (time_after(jiffies, start + adap->timeout)) {
+ /* Test one last time, as we may have been preempted
+ * between last check and timeout test.
+ */
+ if (getscl(adap))
+ break;
return -ETIMEDOUT;
+ }
cond_resched();
}
#ifdef DEBUG