On Tue, Dec 22, 2009 at 4:50 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: > At Tue, 22 Dec 2009 16:34:32 +0900, > jassi brar wrote: >> >> On Mon, Dec 21, 2009 at 8:28 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: >> > At Thu, 17 Dec 2009 17:21:28 +0900, >> > jassi brar wrote: >> >> >> >> On Thu, Dec 17, 2009 at 4:43 PM, Takashi Iwai <tiwai@xxxxxxx> 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@xxxxxxx> wrote: >> >> >> > At Thu, 17 Dec 2009 15:00:02 +0900, >> >> >> > jassisinghbrar@xxxxxxxxx wrote: >> >> >> >> >> >> >> >> From: Jassi Brar <jassi.brar@xxxxxxxxxxx> >> >> >> >> >> >> >> >> 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. >> >> >From what i have seen, every use of sleep is just to kill some time, >> >> i.e, wake_up >> >> is not taken as indication of completion of the purpose. >> > >> > It's used also for poll. >> > >> > Meanwhile, we may change snd_pcm_*_poll() function itself, too... >> How about employing a new snd_pcm_runtime member (say, need_min) which >> denote the _exact_ minimum amount of data needed to serve purpose >> of last sleep ? >> >> Quick idea of what i mean, follows. If you like it, i will resend the >> patches again >> Thanks. > > Well, I don't know. This clearly changes the semantics of avail_min > in the write case. That is, this leads to slight incompatibilities. > Whether such a difference is acceptable on all possible situations is > another question... I think, only applications, that don't call snd_pcm_wait() before blocking writes _and_ count upon the blocking times of such writes, may be affected. Clearly not a serious crime against such apps. Regards. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
