On Mon, 10 Feb 2020 15:04:23 +0100, Peter Ujfalusi wrote:
Some DMA engines can have big FIFOs which adds to the latency. The DMAengine framework can report the FIFO utilization in bytes. Use this information for the delay reporting.
Signed-off-by: Peter Ujfalusi peter.ujfalusi@ti.com
Hi,
5.6-rc1 now have support for reporting the DMA cached data. With this patch we can include it to the delay calculation. The first DMA driver which reports this is the TI K3 UDMA driver.
Regards, Peter
sound/core/pcm_dmaengine.c | 6 ++++++ sound/soc/soc-pcm.c | 2 +- 2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/sound/core/pcm_dmaengine.c b/sound/core/pcm_dmaengine.c index 5749a8a49784..4f1395fd0160 100644 --- a/sound/core/pcm_dmaengine.c +++ b/sound/core/pcm_dmaengine.c @@ -247,9 +247,15 @@ snd_pcm_uframes_t snd_dmaengine_pcm_pointer(struct snd_pcm_substream *substream)
status = dmaengine_tx_status(prtd->dma_chan, prtd->cookie, &state); if (status == DMA_IN_PROGRESS || status == DMA_PAUSED) {
struct snd_pcm_runtime *runtime = substream->runtime;int sample_bits = snd_pcm_format_physical_width(runtime->format);- buf_size = snd_pcm_lib_buffer_bytes(substream); if (state.residue > 0 && state.residue <= buf_size) pos = buf_size - state.residue;
sample_bits *= runtime->channels;runtime->delay = state.in_flight_bytes / (sample_bits / 8);
Can this be simply bytes_to_frames()?
runtime->delay = bytes_to_frames(runtime, state.in_flight_bytes);
}
return bytes_to_frames(substream->runtime, pos); diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c index ff1b7c7078e5..58ef508d70a3 100644 --- a/sound/soc/soc-pcm.c +++ b/sound/soc/soc-pcm.c @@ -1151,7 +1151,7 @@ static snd_pcm_uframes_t soc_pcm_pointer(struct snd_pcm_substream *substream) } delay += codec_delay;
- runtime->delay = delay;
- runtime->delay += delay;
Is it correct? delay already takes runtime->delay as its basis, so it'll result in a double.
thanks,
Takashi