ASoC: omap-mcbsp: Place correct constraints for streams

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@nokia.com>
Acked-by: Jarkko Nikula <jhnikula@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolsfonmicro.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

1 files changed, 77 insertions, 21 deletions

diff --git a/sound/soc/omap/omap-mcbsp.c b/sound/soc/omap/omap-mcbsp.c
index b06d8f1620d7..aebd3af2ab79 100644
--- a/sound/soc/omap/omap-mcbsp.c
+++ b/sound/soc/omap/omap-mcbsp.c
@@ -173,6 +173,50 @@ 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 +229,45 @@ 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;