Doug Ledford wrote:

> 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.
>
>
>
OK, the attached patch should do what is mentioned above.

Doug Ledford