hello takashi, >>>> the brief log is (4 periods of 64 frames): >>>> stream_pointer at 64 >>>> stream_pointer at 128 >>>> stream_pointer at 192 >>>> stream_pointer at 256 >>> This is invalid. The pointer callback must return 0 in this case. >>> The value the pointer callback returns is between 0 and buffer_size-1. >> sry, typo, 5 periods of 64 frames > > Then it must be OK. If the stream is stopped, it's likely by the > buffer underrun detection or so... > > BTW, you should be sure that the buffer size is aligned to the period > size if such a design is assumed. Without the extra constraint, it > could be unaligned as default. now i am trying to debug it some more. the lx6464es card provides commands to send audio buffers to the card, and issues an interrupt, when the buffer has been processed. i am using one dma buffer of period_bytes*periods (128 frames, 3 bytes per sample, 64 channels, 5 periods) for the startup, i am sending a number of buffers to the card (periods): [ 2825.545296] LX6464ES: starting: buffer index 0 on ef620000 (24576 bytes) [ 2825.545385] LX6464ES: starting: buffer index 1 on ef626000 (24576 bytes) [ 2825.545474] LX6464ES: starting: buffer index 2 on ef62c000 (24576 bytes) [ 2825.545568] LX6464ES: starting: buffer index 3 on ef632000 (24576 bytes) [ 2825.545662] LX6464ES: starting: buffer index 4 on ef638000 (24576 bytes) for each buffer, the card issues an `end of buffer' interrupt, in which i send a new buffer to the card and call snd_pcm_period_elapsed with an updated hw pointer: [ 2825.548340] LX6464ES: interrupt: gave buffer index 0 on ef620000 (24576 bytes) [ 2825.548385] LX6464ES: stream_pointer at 128 [ 2825.550986] LX6464ES: interrupt: gave buffer index 1 on ef626000 (24576 bytes) [ 2825.551029] LX6464ES: stream_pointer at 256 [ 2825.553653] LX6464ES: interrupt: gave buffer index 2 on ef62c000 (24576 bytes) [ 2825.553695] LX6464ES: stream_pointer at 384 [ 2825.556353] LX6464ES: interrupt: gave buffer index 3 on ef632000 (24576 bytes) [ 2825.556397] LX6464ES: stream_pointer at 512 [ 2825.559014] LX6464ES: interrupt: gave buffer index 4 on ef638000 (24576 bytes) [ 2825.559061] LX6464ES: stream_pointer at 0 directly after returning 0 from the pointer callback, alsa requests a stop: [ 2825.559067] ->lx_pcm_trigger the timing seems to be fine (2.7 ms for 128 frames). any idea, why alsa wants to stop the transfer? am i missing something, like to i need to inform alsa, that the cyclic buffer wraps around? the code is available at [1] thanks, tim [1] http://tim.klingt.org/git?p=digigram.git;a=shortlog;h=refs/heads/digigram -- tim@xxxxxxxxxx http://tim.klingt.org Relying on the government to protect your privacy is like asking a peeping tom to install your window blinds. John Perry Barlow
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