From: Ben Zhang <benzh@xxxxxxxxxxxx>
Rewrite the ring buffer transfer functions to copy one period
at a time then call snd_pcm_period_elapsed(). This reduces the
latency of transferring the initial ~2sec of audio after hotword
detect since audio samples are available for userspace earlier.
Signed-off-by: Ben Zhang <benzh@xxxxxxxxxxxx>
Signed-off-by: Curtis Malainey <cujomalainey@xxxxxxxxxxxx>
---
sound/soc/codecs/rt5677-spi.c | 91 +++++++++++++++++++++++------------
1 file changed, 60 insertions(+), 31 deletions(-)
diff --git a/sound/soc/codecs/rt5677-spi.c b/sound/soc/codecs/rt5677-spi.c
index 25d75a803cb5..b9b0f646127d 100644
--- a/sound/soc/codecs/rt5677-spi.c
+++ b/sound/soc/codecs/rt5677-spi.c
@@ -51,7 +51,8 @@
#define RT5677_BUF_BYTES_TOTAL 0x20000
#define RT5677_MIC_BUF_ADDR 0x60030000
#define RT5677_MODEL_ADDR 0x5FFC9800
-#define RT5677_MIC_BUF_BYTES (RT5677_BUF_BYTES_TOTAL - sizeof(u32))
+#define RT5677_MIC_BUF_BYTES ((u32)(RT5677_BUF_BYTES_TOTAL - \
+ sizeof(u32)))
#define RT5677_MIC_BUF_FIRST_READ_SIZE 0x10000
static struct spi_device *g_spi;
@@ -205,15 +206,15 @@ static int rt5677_spi_mic_write_offset(u32 *mic_write_offset)
}
/*
- * Copy a block of audio samples from the DSP mic buffer to the dma_area of
- * the pcm runtime. The receiving buffer may wrap around.
+ * Copy one contiguous block of audio samples from the DSP mic buffer to the
+ * dma_area of the pcm runtime. The receiving buffer may wrap around.
* @begin: start offset of the block to copy, in bytes.
* @end: offset of the first byte after the block to copy, must be greater
* than or equal to begin.
*
* Return: Zero if successful, or a negative error code on failure.
*/
-static int rt5677_spi_append_data(struct rt5677_dsp *rt5677_dsp,
+static int rt5677_spi_copy_block(struct rt5677_dsp *rt5677_dsp,
u32 begin, u32 end)
{
struct snd_pcm_runtime *runtime = rt5677_dsp->substream->runtime;
@@ -269,6 +270,38 @@ static int rt5677_spi_append_data(struct rt5677_dsp *rt5677_dsp,
return ret;
}
+/*
+ * Copy a given amount of audio samples from the DSP mic buffer starting at
+ * mic_read_offset, to the dma_area of the pcm runtime. The source buffer may
+ * wrap around. mic_read_offset is updated after successful copy.
+ * @amount: amount of samples to copy, in bytes.
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+static int rt5677_spi_copy(struct rt5677_dsp *rt5677_dsp, u32 amount)
+{
+ int ret = 0;
+ u32 target;
+
+ if (amount == 0)
+ return ret;
+
+ target = rt5677_dsp->mic_read_offset + amount;
+ /* Copy the first chunk in DSP's mic buffer */
+ ret |= rt5677_spi_copy_block(rt5677_dsp, rt5677_dsp->mic_read_offset,
+ min(target, RT5677_MIC_BUF_BYTES));
+
+ if (target >= RT5677_MIC_BUF_BYTES) {
+ /* Wrap around, copy the second chunk */
+ target -= RT5677_MIC_BUF_BYTES;
+ ret |= rt5677_spi_copy_block(rt5677_dsp, 0, target);
+ }
+
+ if (!ret)
+ rt5677_dsp->mic_read_offset = target;
+ return ret;
+}
+
/*
* A delayed work that streams audio samples from the DSP mic buffer to the
* dma_area of the pcm runtime via SPI.
@@ -279,7 +312,7 @@ static void rt5677_spi_copy_work(struct work_struct *work)
container_of(work, struct rt5677_dsp, copy_work.work);
struct snd_pcm_runtime *runtime;
u32 mic_write_offset;
- size_t bytes_copied, period_bytes;
+ size_t new_bytes, copy_bytes, period_bytes;
int ret = 0;
/* Ensure runtime->dma_area buffer does not go away while copying. */
@@ -312,35 +345,31 @@ static void rt5677_spi_copy_work(struct work_struct *work)
RT5677_MIC_BUF_FIRST_READ_SIZE;
}
- /* Copy all new samples from DSP's mic buffer to dma_area */
- bytes_copied = 0;
- if (rt5677_dsp->mic_read_offset < mic_write_offset) {
- /* One chunk in DSP's mic buffer */
- ret |= rt5677_spi_append_data(rt5677_dsp,
- rt5677_dsp->mic_read_offset, mic_write_offset);
- bytes_copied = mic_write_offset - rt5677_dsp->mic_read_offset;
- } else if (rt5677_dsp->mic_read_offset > mic_write_offset) {
- /* Wrap around, two chunks in DSP's mic buffer */
- ret |= rt5677_spi_append_data(rt5677_dsp,
- rt5677_dsp->mic_read_offset,
- RT5677_MIC_BUF_BYTES);
- ret |= rt5677_spi_append_data(rt5677_dsp, 0, mic_write_offset);
- bytes_copied = RT5677_MIC_BUF_BYTES -
- rt5677_dsp->mic_read_offset + mic_write_offset;
- }
- if (ret) {
- dev_err(rt5677_dsp->dev, "Copy failed %d\n", ret);
- goto done;
- }
+ /* Calculate the amount of new samples in bytes */
+ if (rt5677_dsp->mic_read_offset <= mic_write_offset)
+ new_bytes = mic_write_offset - rt5677_dsp->mic_read_offset;
+ else
+ new_bytes = RT5677_MIC_BUF_BYTES + mic_write_offset
+ - rt5677_dsp->mic_read_offset;
- rt5677_dsp->mic_read_offset = mic_write_offset;
- rt5677_dsp->avail_bytes += bytes_copied;
+ /* Copy all new samples from DSP mic buffer, one period at a time */
period_bytes = snd_pcm_lib_period_bytes(rt5677_dsp->substream);
-
- if (rt5677_dsp->avail_bytes >= period_bytes) {
- snd_pcm_period_elapsed(rt5677_dsp->substream);
- rt5677_dsp->avail_bytes = 0;
+ while (new_bytes) {
+ copy_bytes = min(new_bytes, period_bytes
+ - rt5677_dsp->avail_bytes);
+ ret = rt5677_spi_copy(rt5677_dsp, copy_bytes);
+ if (ret) {
+ dev_err(rt5677_dsp->dev, "Copy failed %d\n", ret);
+ goto done;
+ }
+ rt5677_dsp->avail_bytes += copy_bytes;
+ if (rt5677_dsp->avail_bytes >= period_bytes) {
+ snd_pcm_period_elapsed(rt5677_dsp->substream);
+ rt5677_dsp->avail_bytes = 0;
+ }
+ new_bytes -= copy_bytes;
}
+
/* TODO benzh: use better delay time based on period_bytes */
schedule_delayed_work(&rt5677_dsp->copy_work, msecs_to_jiffies(5));
done:
--
2.23.0.187.g17f5b7556c-goog
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
