2012/4/5 David Henningsson <david.henningsson at canonical.com>: > On 04/05/2012 10:59 AM, Feng Wei wrote: >> >> David, >> I'd met xrun on some embedded platform, which will only report hw_ptr >> at period boundary. Maybe it shouldn't use tsched, I'm not sure. Sorry >> for inconvenience. > > > Actually it does raise an important question about how we deal with > platforms that have bad hw_ptr granularity. We don't to that very well > today. > > Also is there much difference, powersave wise, between running in non-tsched > and tsched mode? If there isn't, maybe using non-tsched for your particular > device is the best option (if it works). No much difference, but tsched is the default way. Non-tsched mode works well on my device. I think it's better to provide capability like "accurate hw_ptr" in alsa driver so that we can determine schedule mode at runtime. > > >> >> 2012/4/5 David Henningsson<david.henningsson at canonical.com>: >>> >>> On 04/05/2012 10:22 AM, Feng Wei wrote: >>>> >>>> >>>> When set latency is less than period time, we will assgin working >>>> buffer less than a period size, which will cause unnecessary xrun >>>> and wrong message indicating alsa driver bug. >>> >>> >>> >>> NAK, I don't think this is correct. >>> >>> This is tricky stuff though, so don't take my word for it! ;-) >>> >>> On what machine was this solving a problem for you? >>> >>> Have you verified it leads to better behaviour (or at least not worse) on >>> both tsched and non-tsched systems? >>> >>> I e, try a VOIP call with ~20 ms of latency, on a desktop machine that >>> has 2 >>> x 1s periods, running in tsched mode. I'm guessing the latency will be >>> unacceptable with this patch applied. >>> >>>> >>>> Signed-off-by: Feng Wei<feng.wei at linaro.org> >>>> --- >>>> ?src/modules/alsa/alsa-sink.c ? | ? ?6 +++--- >>>> ?src/modules/alsa/alsa-source.c | ? ?6 +++--- >>>> ?2 files changed, 6 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/src/modules/alsa/alsa-sink.c b/src/modules/alsa/alsa-sink.c >>>> index 5a4b606..a53fb6f 100644 >>>> --- a/src/modules/alsa/alsa-sink.c >>>> +++ b/src/modules/alsa/alsa-sink.c >>>> @@ -953,10 +953,10 @@ static int update_sw_params(struct userdata *u) { >>>> >>>> ? ? ? ? ? ? ?b = pa_usec_to_bytes(latency,&u->sink->sample_spec); >>>> >>>> >>>> - ? ? ? ? ? ?/* We need at least one sample in our buffer */ >>>> + ? ? ? ? ? ?/* We need at least one period and one sample in our buffer >>>> to avoid underflow */ >>>> >>>> - ? ? ? ? ? ?if (PA_UNLIKELY(b< ? ?u->frame_size)) >>>> - ? ? ? ? ? ? ? ?b = u->frame_size; >>>> + ? ? ? ? ? ?if (PA_UNLIKELY(b< ? ?u->frame_size + u->fragment_size)) >>>> + ? ? ? ? ? ? ? ?b = u->frame_size + u->fragment_size; >>>> >>>> ? ? ? ? ? ? ?u->hwbuf_unused = PA_LIKELY(b< ? ?u->hwbuf_size) ? >>>> (u->hwbuf_size - b) : 0; >>>> ? ? ? ? ?} >>>> diff --git a/src/modules/alsa/alsa-source.c >>>> b/src/modules/alsa/alsa-source.c >>>> index 27fd3b9..8c41ca6 100644 >>>> --- a/src/modules/alsa/alsa-source.c >>>> +++ b/src/modules/alsa/alsa-source.c >>>> @@ -876,10 +876,10 @@ static int update_sw_params(struct userdata *u) { >>>> >>>> ? ? ? ? ? ? ?b = pa_usec_to_bytes(latency,&u->source->sample_spec); >>>> >>>> >>>> - ? ? ? ? ? ?/* We need at least one sample in our buffer */ >>>> + ? ? ? ? ? ?/* We need at least one period and one sample in our buffer >>>> to avoid overflow */ >>>> >>>> - ? ? ? ? ? ?if (PA_UNLIKELY(b< ? ?u->frame_size)) >>>> - ? ? ? ? ? ? ? ?b = u->frame_size; >>>> + ? ? ? ? ? ?if (PA_UNLIKELY(b< ? ?u->frame_size + u->fragment_size)) >>>> + ? ? ? ? ? ? ? ?b = u->frame_size + u->fragment_size; >>>> >>>> ? ? ? ? ? ? ?u->hwbuf_unused = PA_LIKELY(b< ? ?u->hwbuf_size) ? >>>> (u->hwbuf_size - b) : 0; >>>> ? ? ? ? ?} >>> >>> >>> >>> >>> >>> -- >>> David Henningsson, Canonical Ltd. >>> http://launchpad.net/~diwic >> >> >> >> > > > > -- > David Henningsson, Canonical Ltd. > http://launchpad.net/~diwic -- Wei.Feng (irc wei_feng) Linaro Multimedia Team Linaro.org???Open source software for ARM SoCs Follow?Linaro:?Facebook?|?Twitter?|?Blog