On 04/03/2015 11:18 PM, Wolfram Sang wrote: > >>> The I2C specs say in 3.1.16 that the recovery procedure should be used >>> when SDA is stuck low. So, I do wonder if we should apply the recovery >>> after a timeout. Stuck SDA might be one reason for timeout, but there >>> may be others... >> >> This is ancient code. And regarding your question - >> Might be it would be reasonable to add call of >> i2c_davinci_wait_bus_not_busy() at the end of i2c_davinci_xfer()? >> This way we will wait for Bus Free before performing recovery. > > That might be an improvement, but the generic question still remains: > Is a timeout a reason for recovery? SDA stuck low is one reason for a > timeout. I have problems making up my mind here between being pragmatic > and being in accordance with the specs. The timeout here means there were no responses from I2C controller within some reasonable time period (default - 1 sec). Which in turn means that Bus/HW state is "unknown" and init&recovery seems reasonable here, but yes - "init&recovery" could be optimized more, but, in my opinion, only as subsequent patches. Actually, i2c_generic_recovery() will just exit if SDA is high already. > >> Of course, i2c_davinci_wait_bus_not_busy() has to be fixed first >> as proposed by Alexander Sverdlin here: >> https://patchwork.ozlabs.org/patch/448994/. > > Okay, good that you said it. So I'll give his patch series priority over > this one. Sorry, but this series already mises few merge windows and it has a lot of revied-by and tested-by, so could we proceed please? Re-based & re-sent http://www.spinics.net/lists/arm-kernel/msg410810.html -- regards, -grygorii -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
