On 2021-09-20 23:29, Mark Brown wrote: > On Mon, Sep 20, 2021 at 09:37:37PM +0200, Peter Rosin wrote: > >> compare if the update was needed at all. But marking volatile wasn't >> enough. I also tried to set both a default and mark as volatile, >> but it seems every read fails with -16 (EBUSY). I don't get why, to me >> it almost feels like a regmap issue of some sort (probably the regmap >> config is bad in some way), but I'm not fluent in regmap... > > Having a default for a volatile register isn't really a sensible > configuration since the whole point with volatile registers is > that they change underneath us, I'd not be surprised if we had > some error checking code in there that was trying to tell you > there was a problem though it does seem like it should at least > be more verbose about it since returning -EBUSY isn't exactly > helpful by itself. I totally agree that it's not a sensible config to set up a register with a default when it's marked as volatile. That was just a wild attempt. I expected it to just work to mark the register as readable and do without the default value (i.e. the way it was before my patch). What I don't understand is why regmap returns -EBUSY in that case. That doesn't make sense to me. Perhaps that -EBUSY is propagated from the I2C layer, but in that case, why is it then ok to do a write to another register at the same spot in the code? So, why -EBUSY? Something is going on that is not understood. At least not by me. Cheers, Peter
