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do snd_pcm_period_elapsed really handle the case when more than one period are elasped ?

For au88x0 , each substream have four sets of hardware registers , it seem that the driver can recover lost interrupt with no underrun when using very small period size

http://www.alsa-project.org/~tiwai/writing-an-alsa-driver/ch05s07.html#pcm-i... http://www.alsa-project.org/%7Etiwai/writing-an-alsa-driver/ch05s07.html#pcm-interface-interrupt-handler-boundary

On calling snd_pcm_period_elapsed()

In both cases, even if more than one period are elapsed, you don't have to call snd_pcm_period_elapsed() many times. Call only once. And the pcm layer will check the current hardware pointer and update to the latest status.

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Yes, the new code handles more alapsed periods, too. The in_interrupt check is mainly for situations when period count == 1 and it compares expected next hw_ptr for interrupt with hw_ptr computed from the hw_base and actual position in the ring buffer.

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				Jaroslav

The value "delta" returned by vortex_adbdma_bufshift() seem to be the number of sub-buffer(periods) elapsed ( the value can be 0 , 1 , 2 or 3 )

when aplay using very small period_size (e.g. 16 ) , the driver write message in system log when delta > 1 (i.e. more than 1 period have been elapsed ) but the sound is still ok since there are two more periods in the sub-buffer

But I cannot see any code in snd_pcm_period_elasped() add two period size to hw_ptr