On Tue, Nov 18, 2014 at 7:23 PM, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote: >>>> As far as I understood, the proposed watermark implementation only >>>> affects the device buffer and as I mentioned above that will not help >>>> with reducing the interrupt rate. >>> >>> >>> >>> By setting the watershed level the userspace application tells you that >>> it >>> is OK with getting data with a higher latency than one sample. This >>> allows >>> the driver to configure the FIFO level and hence reduce the interrupt >>> rate. >>> >> >> Hi Lars, >> >> The implementation (as proposed in the patch by Josselin and Yannick) >> does not inform the driver of changes to watermark, that is only >> visible to core iio / buffer logic. > > > That should be trivial to add though. > True. I've actually started by implementing hardware fifo support as a new type of iio buffer, but I got scared by the buffer demux stuff. I can take another stab at it, if that sounds better? >> >> Also, the watermark alone is not enough to properly support hardware >> fifos: the fifo can operate in multiple modes, we need to read data >> from the hardware fifo even when the watermark interrupt is not issued >> (the flush operation in the current patch set). > > > What kind of modes are there? > Stream - new values overwrrite old values, Fifo - drop new values. -- 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
