未验证 提交 fa1f875c 编写于 作者: P Peter Ujfalusi 提交者: Mark Brown

ALSA: dmaengine_pcm: Consider DMA cache caused delay in pointer callback

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: NPeter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: NTakashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20200210151402.29634-1-peter.ujfalusi@ti.comSigned-off-by: NMark Brown <broonie@kernel.org>
上级 851fd873
......@@ -247,9 +247,14 @@ 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;
buf_size = snd_pcm_lib_buffer_bytes(substream);
if (state.residue > 0 && state.residue <= buf_size)
pos = buf_size - state.residue;
runtime->delay = bytes_to_frames(runtime,
state.in_flight_bytes);
}
return bytes_to_frames(substream->runtime, pos);
......
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