[lkml]   [2011]   [Nov]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [RFC PATCH 1/7] Documentation: add docs for drivers/zio
    zio readme:
    >> + Ctrl: version 0.2, trigger timer, dev zzero, cset 0, chan 2
    >> + Ctrl: seq 102, n 4, size 1, bits 8, flags 01000001 (little-endian)
    >> + Ctrl: stamp 4066.519285605 (0)
    >> + Data: 60 61 62 63

    Jonathan Cameron:
    > Interesting approach to meta data handling. It's kind of 'partly' out
    > of band as it can apply to large chunks of data.

    Exactly. Then, you can ignore the metadata if you want. It's like
    having a line of packed food, with detailed labels. You can read the
    label before getting each content blob, or just read the blob and
    discard the label. Or you can pass everything to someone else, for
    off-line handling.

    We are aware there is a serious overhead if blocks are small, but the
    use case is different, as said.

    > How does it map if you have triggers causing single captures from each
    > channel? I would imagine you will then store a whole meta data set per
    > sample?

    Yes. Worse: csets are acquired (or output) concurrently, so there's
    one control structure per channel (actually, gain and offset may be
    different in each channel, so there's a reason).

    But when blocks are acquired by a hardware card with 256MB of internal
    memory and then transferred in a single DMA burst for offline
    analysis, then the overhead is negligible and I see an advantage in

    Actually, we are considering a buffer that reassembles samples,
    returning bigger blocks on demand, so we get rid of some of the
    overhead. But that's more a stress-test for the buffer concept than
    for real use cases.

    Sure we lack any in-kernel users and don't want to have them in the
    future, that's helping us a lot.

    > I know this isn't your use case, but I'm currious to see where
    > the overlap lies between this and IIO as you can imagine!

    Yes, we are too. Federico has an ad7888 driver working, both for IIO
    and ZIO (and Comedi, but that's out of the game already), and we are
    going to write for a few more IIO-supported devices. In this way we
    both validate (or not) our design and compare with IIO.

    Thank you for your feedback, both here and in the off-list email.


     \ /
      Last update: 2011-11-27 00:13    [W:0.024 / U:0.116 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site