diff options
Diffstat (limited to 'sound/firewire')
| -rw-r--r-- | sound/firewire/amdtp-stream.c | 29 |
1 files changed, 18 insertions, 11 deletions
diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c index fd7c3e4d5374..8a7818130382 100644 --- a/sound/firewire/amdtp-stream.c +++ b/sound/firewire/amdtp-stream.c @@ -176,6 +176,8 @@ int amdtp_stream_add_pcm_hw_constraints(struct amdtp_stream *s, struct snd_pcm_runtime *runtime) { struct snd_pcm_hardware *hw = &runtime->hw; + unsigned int ctx_header_size; + unsigned int maximum_usec_per_period; int err; hw->info = SNDRV_PCM_INFO_BATCH | @@ -196,19 +198,24 @@ int amdtp_stream_add_pcm_hw_constraints(struct amdtp_stream *s, hw->period_bytes_max = hw->period_bytes_min * 2048; hw->buffer_bytes_max = hw->period_bytes_max * hw->periods_min; - /* - * Currently firewire-lib processes 16 packets in one software - * interrupt callback. This equals to 2msec but actually the - * interval of the interrupts has a jitter. - * Additionally, even if adding a constraint to fit period size to - * 2msec, actual calculated frames per period doesn't equal to 2msec, - * depending on sampling rate. - * Anyway, the interval to call snd_pcm_period_elapsed() cannot 2msec. - * Here let us use 5msec for safe period interrupt. - */ + // Linux driver for 1394 OHCI controller voluntarily flushes isoc + // context when total size of accumulated context header reaches + // PAGE_SIZE. This kicks tasklet for the isoc context and brings + // callback in the middle of scheduled interrupts. + // Although AMDTP streams in the same domain use the same events per + // IRQ, use the largest size of context header between IT/IR contexts. + // Here, use the value of context header in IR context is for both + // contexts. + if (!(s->flags & CIP_NO_HEADER)) + ctx_header_size = IR_CTX_HEADER_SIZE_CIP; + else + ctx_header_size = IR_CTX_HEADER_SIZE_NO_CIP; + maximum_usec_per_period = USEC_PER_SEC * PAGE_SIZE / + CYCLES_PER_SECOND / ctx_header_size; + err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_TIME, - 5000, UINT_MAX); + 5000, maximum_usec_per_period); if (err < 0) goto end; |