On Sun, 10 Dec 2017 21:53:42 +0100 Stefan Brüns <stefan.bruens@xxxxxxxxxxxxxx> wrote: > On Sunday, December 10, 2017 6:27:33 PM CET Jonathan Cameron wrote: > > On Fri, 8 Dec 2017 18:41:48 +0100 > > > > Stefan Brüns <stefan.bruens@xxxxxxxxxxxxxx> wrote: > > > Although the datasheet states the CNVR flag is cleared by reading the > > > BUS_VOLTAGE register, it is actually cleared by reading any of the > > > voltage/current/power registers. > > > > > > The behaviour has been confirmed by TI support: > > > http://e2e.ti.com/support/amplifiers/current-shunt-monitors/f/931/p/647053 > > > /2378282 > > > > > > Signed-off-by: Stefan Brüns <stefan.bruens@xxxxxxxxxxxxxx> > > > > I haven't checked the code thoroughly so there may well be something > > stopping it but have you checked the case where the only channel enabled is > > the timestamp? > > > > Obviously it makes little sense, but IIRC there is nothing in the core > > preventing that happening. > > The timestamp is completely unrelated to the status register, so I fail to > understand your question. Can you please clarify? If you only have a timestamp, the trigger will still fire (I think) but you'll do no reading at all from the device. If configured in this, admittedly odd, way you should just get a stream of timestamps with no data. > > This only removes a redundant read. The question is whether it is redundant if we have no non timestamp registers enabled. I'll be honest, whilst I can't immediately spot any protection against this in the core (and it definitely used to be possible), I'm not totally sure it now is and don't have a system to hand to test against. We had some debate a long time back on whether it made sense to have only timestamps and I think we concluded it did as you might in theory only care about the timing and not the data in some obscure cases. Jonathan > > All channel combinations (w/ and w/o timestamp) work, but combinations not > including the power register use less bus time now. > > Kind regards, > > Stefan > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
