commit: 8ee161ce5e0cfc689eb677f227a6248191165fac From: Ville Syrjala <[email protected]> Date: Thu, 15 Mar 2012 18:11:05 +0100 Subject: 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 <[email protected]> Cc: [email protected] Signed-off-by: Jean Delvare <[email protected]> --- drivers/i2c/algos/i2c-algo-bit.c | 8 +++++++- 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 525c734..24f94f4 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 -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
