On Wed, 13 Dec 2017 00:48:40 +0100 Stefan Brüns <stefan.bruens@xxxxxxxxxxxxxx> wrote: > On Tuesday, December 12, 2017 9:15:30 PM CET Jonathan Cameron wrote: > > 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/64 > > > > > 7053 > > > > > /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. > > If there are reads depends on the mode - if running asynchronously, it will > just stream out 64 bits of timestamp each interval. In synchronous mode, the > driver will read the status register (low bits of bus voltage register for > INA219, msk register for INA226), which implicitly clears the CNVR flag. > > > > This only removes a redundant read. > > > > The question is whether it is redundant if we have no non timestamp > > registers enabled. > > According to the documentation, INA219 and 226 had to be treated differently. > As it turned out, both actually behave the same way regarding the CNVR flag, > so we just poll the status register, which for both devices clears the flag. Ah, fine then. I thought we were talking about having to read a channel not just the register we are anyway polling for status. Applied to the togreg branch of iio.git. Thanks, Jonathan > > 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
