mISDN: Add feature via MISDN_CTRL_FILL_EMPTY to fill fifo if empty

This prevents underrun of fifo when filled and in case of an underrun it
prevents subsequent underruns due to jitter.
Improve dsp, so buffers are kept filled with a certain delay, so moderate
jitter will not cause underrun all the time -> the audio quality is highly
improved. tones are not interrupted by gaps anymore, except when CPU is
stalling or in high load.

Signed-off-by: Andreas Eversberg <andreas@eversberg.eu>
Signed-off-by: Karsten Keil <kkeil@suse.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/isdn/mISDN/dsp.h b/drivers/isdn/mISDN/dsp.h
index 6c3fed6b8d4f..ded948069335 100644
--- a/drivers/isdn/mISDN/dsp.h
+++ b/drivers/isdn/mISDN/dsp.h
@@ -198,6 +198,7 @@ struct dsp {
         /* hardware stuff */
         struct dsp_features features;
         int             features_rx_off; /* set if rx_off is featured */
+        int             features_fill_empty; /* set if fill_empty is featured */
         int             pcm_slot_rx; /* current PCM slot (or -1) */
         int             pcm_bank_rx;
         int             pcm_slot_tx;