On Tue, Sep 26, 2017 at 09:50:40AM +1000, Daniel Versick wrote: > Hi, > > I am trying to resolve the known issue of ‘completion timed out’ in the i2c-ismt driver which has been reported a couple of times. I’ve seen few requests referring to it but no working solution yet. > > I can reliably reproduce that problem on an Intel Atom C2xxx-based device and I found out that the driver does not receive interrupts anymore after getting into the timeout state. Even changing the driver to a polling version shows the same behaviour. It just does not receive a status bit change after transaction. So there is no problem with the MSI interrupt system which has been my first guess. > > When being in the timeout state, the SMbus controller seems to be in such a bad condition that I cannot revive it at all. I tried different resets (such as ISMT_GCTRL_SRST and reseting the driver data structures). Only rebooting the device resolves the problem until next occurrence. A scope shows that data and clock lines are high. > > I found a patch on the Internet which slows down the I2C communication by adding a delay to ismt_access. This patch probably refers to a known errata of the Atom S1200 and might work there but is no solution for the problem I am currently facing. > > Are there any ideas or further information which might help? I tend to believe that this might be a silicon issue. Is there anything known? > Lets start with the easy question - What kernel version are you using? Neil > Thanks and regards, > Daniel
