[alsa-devel] 1ca3d59d5a3e762fb1c002bcd912914bc858b430 broke passthrough [Was: Re: ALSA 1.0.25 broke AC3 passthrough?]

[Takashi Iwai]

At Mon, 13 Feb 2012 17:32:03 +1100,
Jean-Yves Avenard wrote:
> 
> Hi there
> 
> Okay, I had time today to test a bit more on what was going on
> 
> On 13 February 2012 00:17, Anssi Hannula <anssi.hannula at iki.fi> wrote:
> 
> > I'm not familiar enough with HDA to comment on the cause of the issue,
> > but out of interest, does the hang really only happen with passthrough,
> > i.e. (AES0 & 0x02) set, or does it happen with a PCM stream with the
> > same parameters as well (and the application(s) just happen to set
> > problematic ALSA parameters only in passthrough mode)?
> 
> Actually, went through over a lot of different type, only to find that
> the problem isn't with passthrough as such, but a combination of the
> prealloc value set and if 16 bits / 32 bits audio.
> 
> 16 bits audio, as soon as the ALSA hardware buffer is set to something
> different than the default 64 (like 4096, the default when using
> Ubuntu)  snd_pcm_write will hang then error.
> 
> 32 bits audio, plays under most combinations tried, except for 5.1 PCM
> where I had to set the prealloc buffer to 1024 and above to get it
> work
> 
> Here are the various mode I tried, the output of the log is for 4096
> prealloc buffer
> 
> For a reminder:
> format=2 -> SND_PCM_FORMAT_S16_LE
> format=10 -> SND_PCM_FORMAT_S32_LE
> 
> AC3 Passthrough: working for 64kB, Not working for: 128, 256, 512,
> 1024, 2048 and 4096
> 2012-02-13 15:58:50.339376 I  ALSA: SetParameters(format=2,
> channels=2, rate=48000, buffer_time=500000, period_time=4)
> 2012-02-13 15:58:50.339437 I  ALSA: Buffer size range from 64 to 1048576
> 2012-02-13 15:58:50.339441 I  ALSA: Period size range from 32 to 524288
> 2012-02-13 15:58:50.339455 I  ALSA: Buffer time = 500000 us
> 2012-02-13 15:58:50.339465 I  ALSA: Period time = 4 periods
> 2012-02-13 15:58:50.458098 I  ALSA: Buffer size = 24000 | Period size = 6000
> 2012-02-13 15:58:50.696838 I  AO: Audio fragment size: 12000
> 
> 16 bits stereo: working for 64, Not working for: 128, 256, 512, 1024, 2048, 4096
> 2012-02-13 16:20:39.027793 I  ALSA: SetParameters(format=2,
> channels=2, rate=48000, buffer_time=500000, period_time=4)
> 2012-02-13 16:20:39.027855 I  ALSA: Buffer size range from 64 to 1048576
> 2012-02-13 16:20:39.027859 I  ALSA: Period size range from 32 to 524288
> 2012-02-13 16:20:39.027873 I  ALSA: Buffer time = 500000 us
> 2012-02-13 16:20:39.027883 I  ALSA: Period time = 4 periods
> 2012-02-13 16:20:39.267237 I  ALSA: Buffer size = 24000 | Period size = 6000
> 2012-02-13 16:20:39.507467 I  AO: Audio fragment size: 12000
> 
> 32 bits Stereo: working for: 64, 128,,256, 512, 1024, 2048 and 4096
> 2012-02-13 16:05:25.010312 I  ALSA: SetParameters(format=10,
> channels=2, rate=48000, buffer_time=500000, period_time=4)
> 2012-02-13 16:05:25.010372 I  ALSA: Buffer size range from 32 to 524288
> 2012-02-13 16:05:25.010376 I  ALSA: Period size range from 16 to 262144
> 2012-02-13 16:05:25.010389 I  ALSA: Buffer time = 500000 us
> 2012-02-13 16:05:25.010400 I  ALSA: Period time = 4 periods
> 2012-02-13 16:05:25.286857 I  ALSA: Buffer size = 24000 | Period size = 6000
> 2012-02-13 16:05:25.526849 I  AO: Audio fragment size: 24000
> 
> 5.1 16 bits PCM:
> Using 64kB prealloc buffer, snd_pcm_hw_params_set_buffer_time_near
> gives the error "Invalid Parameter" for 500000
> Not working for 128, 256, 512, 1024, 2048 and 4096
> 
> 2012-02-13 16:09:11.621562 I  ALSA: SetParameters(format=2,
> channels=6, rate=48000, buffer_time=500000, period_time=4)
> 2012-02-13 16:09:11.621628 I  ALSA: Buffer size range from 22 to 349525
> 2012-02-13 16:09:11.621632 I  ALSA: Period size range from 11 to 174762
> 2012-02-13 16:09:11.621645 I  ALSA: Buffer time = 500000 us
> 2012-02-13 16:09:11.621663 I  ALSA: Period time = 4 periods
> 2012-02-13 16:09:11.796861 I  ALSA: Buffer size = 24000 | Period size = 6000
> 2012-02-13 16:09:12.036842 I  AO: Audio fragment size: 36000
> 
> 5.1 32 bits PCM:
> Not working for: 64, 256, 512. Working for 1024, 2048, 4096
> 128 gives Invalid argument for snd_pcm_hw_params_set_buffer_time_near
> 
> 2012-02-13 16:25:12.890306 I  ALSA: SetParameters(format=10,
> channels=6, rate=48000, buffer_time=500000, period_time=4)
> 2012-02-13 16:25:12.890366 I  ALSA: Buffer size range from 12 to 174762
> 2012-02-13 16:25:12.890370 I  ALSA: Period size range from 6 to 87381
> 2012-02-13 16:25:12.890383 I  ALSA: Buffer time = 500000 us
> 2012-02-13 16:25:12.890393 I  ALSA: Period time = 4 periods
> 2012-02-13 16:25:13.066855 I  ALSA: Buffer size = 24000 | Period size = 6000
> 2012-02-13 16:25:13.316823 I  AO: Audio fragment size: 72000
> 
> >From looking at hda_intel.c, it seems that the problem is that the
> nvidia set AZX_DCAPS_BUFSIZE in driver_caps when it probably doesn't
> support it..

The problem of Nvidia HDMI and the buffer-alignment was already fixed
in the upstream code.  Nvidia HDMI is known to be broken with the
arbitrary alignment, so it's disabled automatically.

> Hopefully Stephen will be able to answer that one.
> 
> I'm surprised not more people has reported the problem, surely there
> are a lot of people affected by this... Though 1.0.25 is very recent
> and not used yet by many linux distribution. Soon this will change :(

Maybe little people are actually using the released alsa-driver any
longer.


Takashi