On Wed, Mar 25, 2015 at 05:15:04PM +0100, Wolfram Sang wrote: > Guenter, > > thanks for the update > > > Ultimately, the real problem is how i2c-dev accesses a client, not how > > i2c client drivers (who assume they have exclusive access to a chip) > > handle multi-command sequences. Forcing extensive locking on all drivers > > because of i2c-dev just doesn't seem to be the right thing to do. > > I agree. i2c-dev is too much of a special case. > > And since at24 has its own lock (I missed that), your patch might as > well be good enough to be applied, I'd think. > Ah, sorry, I blindly assumed that you are aware of that. Yes, at24 itself is not the problem, it is parallel access to the chip by i2c-dev. The same is actually true for all the other drivers I looked at; usually they have their own lock(s), but such locks do not protect against interference by i2c-dev. The bad part is that i2c-dev is heavily used by user space at my workplace, and that code happily messes with chips which are also handled by kernel drivers. But as I said, I have no real good idea how to fix that - neither the user-space code nor how i2c-dev interfers with (or completely messes up) device access by drivers. Thanks, Guenter -- 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
