> >> + - defeature-repeated-start: Include this property to defeature repeated start > >> + This defeature is due to a few bugs in the > >> + I2C controller. > >> + Completion interrupt after a read/receive > >> + operation is NOT obtained if HOLD bit is set > >> + at that time. Because of this bug, repeated start > >> + will only work if there are no transfers following > >> + a read/receive transfer. > >> + If HOLD is held for long without a transfer, > >> + invalid read transactions are generated by the > >> + controller due to a HW timeout related bug. > > > > I'm not keen on the name; it sounds like we're disabling a feature > > rather than describing the problem (and "defeature" is not a common > > term in this sense, "disable" would be better). > > > > It sounds like there are two issues with staying in the HOLD state? Lost > > completion IRQs and a separate HW timeout bug? Or are the two related? > > > > Yes, there are two issues here and they are not related. > But a combination of both is leading to not using repeated start. > The intention was to defeature except that it works in some scenarios > (such as a typical write+read in that order with repeated start) > and there are people who already use the driver with slaves that need this. That should not be handled using a binding. If you get a transfer (at runtime) with criteria you don't support, return with -EOPNOTSUPP from the master xfer routine. That being said, the number of broken/not-fully-compliant I2C controllers has increased a lot recent times (why can't we just use the established old ones?). Maybe we will have core support for a subset of I2C (wr+rd) in the future, but that's still ahead...
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