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    SubjectRe: [PATCH] i810_audio fix for version 0.11
    Nathan Bryant wrote:

    > Andris Pavenis wrote:
    >
    >> > With this patch, it seems to work fine. Without, it hangs on write.
    >>
    >> I met case when dmabuf->count==0 when __start_dac() is called. As result
    >> I still got system freezing even if PCM_ENABLE_INPUT or
    >> PCM_ENABLE_OUTPUT were set accordingly (I used different patch, see
    >> another patch I sent today).
    >>
    >> My latest revision of patch "survives" without problems already some
    >> hours (normally I'm not listening radio through internet all time,
    >> but this time I do ...)
    >>
    >> Andris
    >>
    >>
    >>
    >>
    >>
    >>
    >
    > i knew i shoula been a little less lazy with that one...
    >
    > haven't looked at your revision yet but we should just clean up and
    > make update_lvi self-contained so that it always does *something*
    > appropriate regardless of state. maybe that's what you did. ;-)
    >
    > (fyi, i'm not subscribed to linux-kernel, too much volume for the few
    > specific interests i have, i don't see some of this stuff until, and
    > if, i go digging thru archives)
    >
    Well, unfortunately, neither of the patches you guys sent do what I was
    looking for ;-) My goal with that code was to enable a specific certain
    behaviour, and because of the deadlock I have to make a few changes
    elsewhere for it to work properly. The workaround patches are fine for
    now, but later today I'll make a 0.12 that fixes it the way I'm looking
    for. (Hint: it's legal for a program to call SETTRIGGER to disable PCM
    output, then call the write() routine to fill the buffer, then call
    SETTRIGGER again to start output, otherwise known as pre buffering, and
    I want to support that without forcing the DAC to be started on
    update_lvi())

    The real answer is multipart:

    1) during i810_open go back to the old behaviour of setting
    dmabuf->trigger to PCM_ENABLE_INPUT and/or OUTPUT based on file mode.

    2) make sure that i810_mmap clears dmabuf->trigger

    3) make sure that in both i810_write and i810_read, we force the trigger
    setting when we can't output/input any data because count <= 0

    4) in update_lvi make the check something like:

    if (!dmabuf->enable && dmabuf->trigger) {
    ....
    }

    That should solve the problem, I just haven't written it up yet.



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