[alsa-devel] my driver can't reproduce continuously

[Takashi Iwai]

At Mon, 27 Jul 2009 09:58:19 +0900,
Kuninori Morimoto wrote:
> 
> 
> Dear Takashi
> 
> Thank you for your comment
> 
> > My rough guess is that your pointer callback returns a wrong value.
> > The pointer callback is supposed to give the currently played position
> > offset in a ring buffer, and ranged from 0 to buffer_size-1.
> > When the first snd_pcm_period_elapsed() is called, it should be
> > (ideally) pointing at period_size, at the succeeding calls,
> > period_size*2, period_size*3, then 0 again.
> 
> The criminal is my wrong understanding...
> OK.
> 
> But I still have trouble now.
> 
> follows the log
> ------------
> trigger called
> hw_prt_base = 0, hw_prt = 127, appl_prt = 8192
> hw_prt_base = 0, hw_prt = 255, appl_prt = 8319
> (snip)
> hw_prt_base = 0, hw_prt = 3845, appl_prt = 11888
> hw_prt_base = 0, hw_prt = 3995, appl_prt = 12037
> call elapsed                                         // 2nd call
> hw_prt_base = 0, hw_prt = 4123, appl_prt = 12037
> hw_prt_base = 0, hw_prt = 4272, appl_prt = 12187
> call elapsed                                         // 3rd call
> hw_prt_base = 0, hw_prt = 6202, appl_prt = 12288
> call elapsed                                         // 4th call
> hw_prt_base = 8192, hw_prt = 8192, appl_prt = 12288
> <<< driver stopped here... >>
> ------------
> 
> when 1st buffer was send,
> driver stop.
> 2nd trigger function isn't called.

Check the raw value returned from the pointer callback, too.
This can be the real cause.


Takashi