[alsa-devel] Problem bringing up new alsa driver

Lee Revell rlrevell at joe-job.com
Fri Apr 24 06:40:19 CEST 2009

2009/4/23 Jon Smirl <jonsmirl at gmail.com>:
> My new ALSA driver is playing the first three samples in a loop. It's
> not progressing forward in the wav file.  It's behaving like I'm not
> calling snd_pcm_period_elapsed() but I have a printk() in it so I'm
> sure it is being called. Later samples are not getting copied into the
> DMA buffer,
> Can anyone give me a clue as to what to look for?
> root at phyCORE-MPC5200B-tiny:~ aplay phone.wav
> snd_pcm_playback_open
> snd_pcm_open
> snd_pcm_open_file
> snd_pcm_open_substream
> mpc5200-psc-ac97 f0002200.sound: psc_dma_startup(substream=c78bd800)
> mpc5200-psc-ac97 f0002200.sound: psc_dma_pcm_open(substream=c78bd800)
> Playing WAVE 'phone.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo
> mpc5200-psc-ac97 f0002200.sound:
> psc_ac97_hw_analog_params(substream=c78bd800) p_size=5513
> p_bytes=22052 periods=3 buffer_size=22050  buffer_bytes=88200

Your buffer is 4x the period size, but periods=3.  Off by one error somewhere?


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