Re: [PATCH] Fixes: Re: intel8x0 has stopped working.

[Takashi Iwai <tiwai@suse.de>]

At Thu, 5 Feb 2004 14:15:22 -0500,
Glenn Maynard wrote:
> 
> On Thu, Feb 05, 2004 at 12:01:28PM +0100, Jaroslav Kysela wrote:
> > > My point is, I don't think setting start_threshold to buffer_size is 
> > > even "wrong" at all. Some people might want the buffer to be full before 
> > > it starts, and my patch allows for that.
> > 
> > It's not wrong semantics. I see - it's logical, but I don't want to follow
> > some rule as some API designers does - control magically some things. I
> > want that developer which uses our API knows what the library / driver
> > exactly does.
> > 
> > We have clear conditions when the stream is started. That's it.
> 
> If this isn't guaranteed to work, I'd suggest making it never work.
> Otherwise, programs will work on some hardware and not others, which is
> a case that should be minimized as much as possible; it's these kinds
> of subtle differences that make it very hard to write reliable (sound,
> video, etc) code.  I've had to play games with setting hardware settings:
> always set the sample rate even if I don't care, use a 32k buffer size
> and not a 4k or 8k one--in order to make it work on as many systems as
> possible without failing mysteriously or triggering alsa-lib asserts.
> 
> (I don't quite understand why start_threashold == buffer_size doessn't
> mean "start when the buffer is full", though.)

because the buffer size is not always aligned to the period size.

when the buffer size is not aligned to period size, the condition will
be never satisfied since start_threshold is checked only when
interrupt occurs (i.e. on period boundary).

maybe we can check such a condition and return an error...


Takashi


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