Messages in this thread | | | Date | Fri, 07 Dec 2001 12:55:19 -0500 | From | Doug Ledford <> | Subject | Re: [PATCH] i810_audio fix for version 0.11 |
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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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