[pulseaudio-discuss] [alsa-devel] [RFC] disabling ALSA period interrupts

pl bossart bossart.nospam at gmail.com
Tue May 11 21:00:14 PDT 2010

Here's a proposal for an alsa-lib modification to allow applications
to disable interrupts (if the hardware can do so).
I used the flag field in hw_params, this looked like a good candidate
to convey this information needed by the driver. I don't really like
adding two new routines, but I don't think there's any other way.
Still 2 points to be worked out:
- I couldn't figure out how to make these two new symbols known to
PulseAudio. Somehow there's a missing symbol that prevents PA modules
from loading, not sure where it needs to be declare
- I thought I could make use of the same flag on the driver side, but
the code in pcm_native.c makes a peculiar use of hw_params->flag. It
looks like this field is used as an internal variable.

for (k = 0; k < constrs->rules_num; k++) {
			struct snd_pcm_hw_rule *r = &constrs->rules[k];
			unsigned int d;
			int doit = 0;
			if (r->cond && !(r->cond & params->flags))
There's too much history for me to figure out what this is supposed to
mean. Am I following a false lead and should I use the more complex
mask array instead?
Thanks for your feedback.
- Pierre
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