I have seen that alsa-driver-0.9.0rc1 cs4281.c driver supports only 2 periods.
There exists an unofficial patch for alsa-driver-0.5.12a done by
[EMAIL PROTECTED] I have seen that some parts of it are included in
0.9.0rc1, some are obsolete, but the limit of only 2 periods is not fixed in
0.9.0rc1 (playback).
Especially snd_cs4281_start_new_dma(cs4281_t *chip, cs4281_dma_t *dma) and
changes to the interrupt handler are not in 0.9.0rc1 (and I believe also not in
CVS).
I am trying to backport it now, but it seems some interfaces have changed.
For exaple what the "pointer" function should return?
I do not understand the following code in alsa-kernel/core/pcm_lib.c:
new_hw_ptr = runtime->hw_ptr_base + pos;
hw_ptr_interrupt = runtime->hw_ptr_interrupt + runtime->period_size;
delta = hw_ptr_interrupt - new_hw_ptr;
if (delta > 0) {
if (delta < runtime->buffer_size / 2) {
snd_printd("Unexpected hw_pointer value (stream = %i, delta: -%ld,
max jitter = %ld): wrong interrupt acknowledge?\n", substream->stream,
(long) delta, runtime->buffer_size /
2);
return
0;
}
runtime->hw_ptr_base += runtime->buffer_size;
if (runtime->hw_ptr_base == runtime->boundary)
runtime->hw_ptr_base = 0;
new_hw_ptr = runtime->hw_ptr_base + pos;
}
runtime->status->hw_ptr = new_hw_ptr;
runtime->hw_ptr_interrupt = new_hw_ptr - (runtime->hw_ptr_base + pos) %
runtime->period_size;
Why is runtime->buffer_size the whole buffer or the period size? What is in
bytes, what in frames? Is there any function/field giving size of a single
frame in bytes?
Best regards,
--
Tomasz Motylewski
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