Dropouts at 192 kHz

[koalo]

Copied from forum:

Hi,

I got the driver working with a Y2 dac and and an external bit clock and my own codec driver. It works great, thanks to all who contributed!

The one problem I had was that at higher sampling frequencies it started to have drop outs. Looking at hw_params I noticed that the buffer at 192kHz seemed smaller than the one for 44.1kHz:
root@pi:/proc/asound/sndrpibclkdiv/pcm0p/sub0# cat hw_params
access: RW_INTERLEAVED
format: S16_LE
subformat: STD
channels: 2
rate: 44100 (44100/1)
period_size: 4410
buffer_size: 22050
root@pi:/proc/asound/sndrpibclkdiv/pcm0p/sub0# cat hw_params
access: RW_INTERLEAVED
format: S32_LE
subformat: STD
channels: 2
rate: 192000 (192000/1)
period_size: 4096
buffer_size: 16384

Then I changed buffer_bytes_max in bcm2708-pcm.c:
.buffer_bytes_max = 1024 * 1024,

Now I get perfect playback at 192kHz and alsa reports the following:
root@pi:/proc/asound/sndrpibclkdiv/pcm0p/sub0# cat hw_params
access: RW_INTERLEAVED
format: S32_LE
subformat: STD
channels: 2
rate: 192000 (192000/1)
period_size: 8000
buffer_size: 96000

Leon