OMAP McBSP FIFO is word structured:
McBSP2 has 1024 + 256 = 1280 word long buffer,
McBSP1,3,4,5 has 128 word long buffer
This means, that the size of the FIFO
depends on the McBSP word size configuration.
For example on McBSP3:
16bit samples: size is 128 * 2 = 256 bytes
32bit samples: size is 128 * 4 = 512 bytes
It is simpler to place constraint for buffer and period based on channels.
McBSP3 as example again (16 or 32 bit samples):
1 channel (mono): size is 128 frames (128 words)
2 channels (stereo): size is 128 / 2 = 64 frames (2 * 64 words)
4 channels: size is 128 / 4 = 32 frames (4 * 32 words)
Use the second method to place hw_rule on buffer size, and in threshold
mode to period size.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxxxxx>
---
sound/soc/omap/omap-mcbsp.c | 99 ++++++++++++++++++++++++++++++++++---------
1 files changed, 78 insertions(+), 21 deletions(-)
diff --git a/sound/soc/omap/omap-mcbsp.c b/sound/soc/omap/omap-mcbsp.c
index b06d8f1..8a55c9a 100644
--- a/sound/soc/omap/omap-mcbsp.c
+++ b/sound/soc/omap/omap-mcbsp.c
@@ -173,6 +173,51 @@ static void omap_mcbsp_set_threshold(struct snd_pcm_substream *substream)
omap_mcbsp_set_rx_threshold(mcbsp_data->bus_id, words);
}
+static int omap_mcbsp_hwrule_min_buffersize(struct snd_pcm_hw_params *params,
+ struct snd_pcm_hw_rule *rule)
+{
+ struct snd_interval *buffer_size = hw_param_interval(params,
+ SNDRV_PCM_HW_PARAM_BUFFER_SIZE);
+ struct snd_interval *channels = hw_param_interval(params,
+ SNDRV_PCM_HW_PARAM_CHANNELS);
+ struct omap_mcbsp_data *mcbsp_data = rule->private;
+ struct snd_interval frames;
+ int size;
+
+ snd_interval_any(&frames);
+ size = omap_mcbsp_get_fifo_size(mcbsp_data->bus_id);
+
+ frames.min = size / channels->min;
+ frames.integer = 1;
+ return snd_interval_refine(buffer_size, &frames);
+
+}
+
+static int omap_mcbsp_hwrule_max_periodsize(struct snd_pcm_hw_params *params,
+ struct snd_pcm_hw_rule *rule)
+{
+ struct snd_interval *period_size = hw_param_interval(params,
+ SNDRV_PCM_HW_PARAM_PERIOD_SIZE);
+ struct snd_interval *channels = hw_param_interval(params,
+ SNDRV_PCM_HW_PARAM_CHANNELS);
+ struct snd_pcm_substream *substream = rule->private;
+ struct snd_soc_pcm_runtime *rtd = substream->private_data;
+ struct snd_soc_dai *cpu_dai = rtd->dai->cpu_dai;
+ struct omap_mcbsp_data *mcbsp_data = to_mcbsp(cpu_dai->private_data);
+ struct snd_interval frames;
+ int size;
+
+ snd_interval_any(&frames);
+ if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+ size = omap_mcbsp_get_max_tx_threshold(mcbsp_data->bus_id);
+ else
+ size = omap_mcbsp_get_max_rx_threshold(mcbsp_data->bus_id);
+
+ frames.max = size / channels->min;
+ frames.integer = 1;
+ return snd_interval_refine(period_size, &frames);
+}
+
static int omap_mcbsp_dai_startup(struct snd_pcm_substream *substream,
struct snd_soc_dai *dai)
{
@@ -185,33 +230,45 @@ static int omap_mcbsp_dai_startup(struct snd_pcm_substream *substream,
if (!cpu_dai->active)
err = omap_mcbsp_request(bus_id);
+ /*
+ * OMAP3 McBSP FIFO is word structured.
+ * McBSP2 has 1024 + 256 = 1280 word long buffer,
+ * McBSP1,3,4,5 has 128 word long buffer
+ * This means that the size of the FIFO depends on the sample format.
+ * For example on McBSP3:
+ * 16bit samples: size is 128 * 2 = 256 bytes
+ * 32bit samples: size is 128 * 4 = 512 bytes
+ * It is simpler to place constraint for buffer and period based on
+ * channels.
+ * McBSP3 as example again (16 or 32 bit samples):
+ * 1 channel (mono): size is 128 frames (128 words)
+ * 2 channels (stereo): size is 128 / 2 = 64 frames (2 * 64 words)
+ * 4 channels: size is 128 / 4 = 32 frames (4 * 32 words)
+ */
if (cpu_is_omap343x()) {
int dma_op_mode = omap_mcbsp_get_dma_op_mode(bus_id);
- int max_period;
/*
- * McBSP2 in OMAP3 has 1024 * 32-bit internal audio buffer.
- * Set constraint for minimum buffer size to the same than FIFO
- * size in order to avoid underruns in playback startup because
- * HW is keeping the DMA request active until FIFO is filled.
- */
- if (bus_id == 1)
- snd_pcm_hw_constraint_minmax(substream->runtime,
- SNDRV_PCM_HW_PARAM_BUFFER_BYTES,
- 4096, UINT_MAX);
-
- if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
- max_period = omap_mcbsp_get_max_tx_threshold(bus_id);
- else
- max_period = omap_mcbsp_get_max_rx_threshold(bus_id);
-
- max_period++;
- max_period <<= 1;
+ * The first rule is for the buffer size, we should not allow
+ * smaller buffer than the FIFO size to avoid underruns
+ */
+ snd_pcm_hw_rule_add(substream->runtime, 0,
+ SNDRV_PCM_HW_PARAM_CHANNELS,
+ omap_mcbsp_hwrule_min_buffersize,
+ mcbsp_data,
+ SNDRV_PCM_HW_PARAM_BUFFER_SIZE, -1);
+ /*
+ * In case of threshold mode, the rule will ensure, that the
+ * period size is not bigger than the maximum allowed threshold
+ * value.
+ */
if (dma_op_mode == MCBSP_DMA_MODE_THRESHOLD)
- snd_pcm_hw_constraint_minmax(substream->runtime,
- SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
- 32, max_period);
+ snd_pcm_hw_rule_add(substream->runtime, 0,
+ SNDRV_PCM_HW_PARAM_CHANNELS,
+ omap_mcbsp_hwrule_max_periodsize,
+ substream,
+ SNDRV_PCM_HW_PARAM_PERIOD_SIZE, -1);
}
return err;
--
1.7.1
--
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