ALSA: ASoC Blackfin: fix bug - Audio Latency on AD1981 with MMAP enabled
With MMAP enabled (DMA mode) on the AD1981, there is +/- 250ms of delay between
writing data to alsa and audio starts coming out of the AD1981.
Copy more data to local buffer before starting DMA
Signed-off-by: Cliff Cai <cliff.cai@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/soc/blackfin/bf5xx-ac97-pcm.c b/sound/soc/blackfin/bf5xx-ac97-pcm.c
index 51f4907..25e50d2 100644
--- a/sound/soc/blackfin/bf5xx-ac97-pcm.c
+++ b/sound/soc/blackfin/bf5xx-ac97-pcm.c
@@ -56,6 +56,7 @@
sport->tx_pos += runtime->period_size;
if (sport->tx_pos >= runtime->buffer_size)
sport->tx_pos %= runtime->buffer_size;
+ sport->tx_delay_pos = sport->tx_pos;
} else {
bf5xx_ac97_to_pcm(
(struct ac97_frame *)sport->rx_dma_buf + sport->rx_pos,
@@ -72,7 +73,15 @@
struct snd_pcm_substream *pcm = data;
#if defined(CONFIG_SND_MMAP_SUPPORT)
struct snd_pcm_runtime *runtime = pcm->runtime;
+ struct sport_device *sport = runtime->private_data;
bf5xx_mmap_copy(pcm, runtime->period_size);
+ if (pcm->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+ if (sport->once == 0) {
+ snd_pcm_period_elapsed(pcm);
+ bf5xx_mmap_copy(pcm, runtime->period_size);
+ sport->once = 1;
+ }
+ }
#endif
snd_pcm_period_elapsed(pcm);
}
@@ -114,6 +123,10 @@
static int bf5xx_pcm_hw_free(struct snd_pcm_substream *substream)
{
+ struct snd_pcm_runtime *runtime = substream->runtime;
+
+ if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+ memset(runtime->dma_area, 0, runtime->buffer_size);
snd_pcm_lib_free_pages(substream);
return 0;
}
@@ -127,16 +140,11 @@
* SPORT working in TMD mode(include AC97).
*/
#if defined(CONFIG_SND_MMAP_SUPPORT)
- size_t size = bf5xx_pcm_hardware.buffer_bytes_max
- * sizeof(struct ac97_frame) / 4;
- /*clean up intermediate buffer*/
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
- memset(sport->tx_dma_buf, 0, size);
sport_set_tx_callback(sport, bf5xx_dma_irq, substream);
sport_config_tx_dma(sport, sport->tx_dma_buf, runtime->periods,
runtime->period_size * sizeof(struct ac97_frame));
} else {
- memset(sport->rx_dma_buf, 0, size);
sport_set_rx_callback(sport, bf5xx_dma_irq, substream);
sport_config_rx_dma(sport, sport->rx_dma_buf, runtime->periods,
runtime->period_size * sizeof(struct ac97_frame));
@@ -164,8 +172,12 @@
pr_debug("%s enter\n", __func__);
switch (cmd) {
case SNDRV_PCM_TRIGGER_START:
- if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+ if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+ bf5xx_mmap_copy(substream, runtime->period_size);
+ snd_pcm_period_elapsed(substream);
+ sport->tx_delay_pos = 0;
sport_tx_start(sport);
+ }
else
sport_rx_start(sport);
break;
@@ -198,7 +210,7 @@
#if defined(CONFIG_SND_MMAP_SUPPORT)
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
- curr = sport->tx_pos;
+ curr = sport->tx_delay_pos;
else
curr = sport->rx_pos;
#else
@@ -237,6 +249,21 @@
return ret;
}
+static int bf5xx_pcm_close(struct snd_pcm_substream *substream)
+{
+ struct snd_pcm_runtime *runtime = substream->runtime;
+ struct sport_device *sport = runtime->private_data;
+
+ pr_debug("%s enter\n", __func__);
+ if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+ sport->once = 0;
+ memset(sport->tx_dma_buf, 0, runtime->buffer_size * sizeof(struct ac97_frame));
+ } else
+ memset(sport->rx_dma_buf, 0, runtime->buffer_size * sizeof(struct ac97_frame));
+
+ return 0;
+}
+
#ifdef CONFIG_SND_MMAP_SUPPORT
static int bf5xx_pcm_mmap(struct snd_pcm_substream *substream,
struct vm_area_struct *vma)
@@ -272,6 +299,7 @@
struct snd_pcm_ops bf5xx_pcm_ac97_ops = {
.open = bf5xx_pcm_open,
+ .close = bf5xx_pcm_close,
.ioctl = snd_pcm_lib_ioctl,
.hw_params = bf5xx_pcm_hw_params,
.hw_free = bf5xx_pcm_hw_free,
diff --git a/sound/soc/blackfin/bf5xx-ac97.c b/sound/soc/blackfin/bf5xx-ac97.c
index c782e31..5e5aafb 100644
--- a/sound/soc/blackfin/bf5xx-ac97.c
+++ b/sound/soc/blackfin/bf5xx-ac97.c
@@ -129,7 +129,6 @@
struct ac97_frame *nextwrite;
sport_incfrag(sport, &nextfrag, 1);
- sport_incfrag(sport, &nextfrag, 1);
nextwrite = (struct ac97_frame *)(sport->tx_buf + \
nextfrag * sport->tx_fragsize);
diff --git a/sound/soc/blackfin/bf5xx-sport.h b/sound/soc/blackfin/bf5xx-sport.h
index 4c16345..fcadcc0 100644
--- a/sound/soc/blackfin/bf5xx-sport.h
+++ b/sound/soc/blackfin/bf5xx-sport.h
@@ -123,6 +123,8 @@
int rx_pos;
unsigned int tx_buffer_size;
unsigned int rx_buffer_size;
+ int tx_delay_pos;
+ int once;
#endif
void *private_data;
};