Hi,
I already pulled it, but below are some comments.
At Mon, 29 Sep 2008 14:44:31 +0100, Mark Brown wrote:
From: Cliff Cai cliff.cai@analog.com
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 snd_pcm_period_elapsed(pcm); } @@ -114,6 +123,10 @@ static int bf5xx_pcm_hw_params(struct snd_pcm_substream *substream,
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);
Missing indentation here.
@@ -164,8 +172,12 @@ static int bf5xx_pcm_trigger(struct snd_pcm_substream *substream, int cmd) 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);
Calling this in the trigger callback is pretty tricky. I guess this could be implemented without involving snd_pcm_period_elapsed(), but rather only inside this machine driver, if it's only the question of dummy data handling at the beginning.
@@ -237,6 +249,21 @@ static int bf5xx_pcm_open(struct snd_pcm_substream *substream) 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;
+}
Better to clear buffers in hw_free in both playback and capture cases (unless you have any issue against it). The hw_free is supposed to be called anyway before closing, so you don't need the same thing in multiple places.
As mentioned, I already pulled the patches, so please make changes against the latest tree.
thanks,
Takashi