[alsa-devel] [PATCH 1/2] ALSA: pcm - Ensure wakeup at each periodic interrupt

[jassi brar]

On Thu, Dec 17, 2009 at 4:43 PM, Takashi Iwai <tiwai at suse.de> wrote:
> At Thu, 17 Dec 2009 16:31:08 +0900,
> jassi brar wrote:
>>
>> On Thu, Dec 17, 2009 at 4:02 PM, Takashi Iwai <tiwai at suse.de> wrote:
>> > At Thu, 17 Dec 2009 15:00:02 +0900,
>> > jassisinghbrar at gmail.com wrote:
>> >>
>> >> From: Jassi Brar <jassi.brar at samsung.com>
>> >>
>> >> The check for at least 'avail_min' available data before calling wake_up
>> >> doesn't always hold good as it does not guarantee callbacks at each periodic
>> >> interrupt.
>> >
>> > Well, avail_min can be greater than period_size.  And, avail_min won't be
>> > less than period size.
>> >
>> > For example, when avail_min = 2.5 x period_size, the driver wakes up
>> > in periods like 3, 2, 3, 2, ...
>> correct, but if we ensure wake_up's after each period and let the 'sleepers'
>> track if the data available is enough or not, we will have more fine grained
>> control.
>> The point is:- Waking up _after_ avail_min is working, but does waking up before
>> avail_min(but at period boundary) break the system?
>
> PulseAudio may complain :)
I meant effects on ALSA state-machine within the kernel.