[alsa-devel] [PATCH v2 2/3] ASoC: pcm: Export parameter intersection logic

[Samuel Holland]

The logic to calculate the subset of stream parameters supported by all
DAIs associated with a PCM stream is nontrivial. Export a helper
function so it can be used to set up simple codec2codec DAI links.

Signed-off-by: Samuel Holland <samuel at sholland.org>
---
 include/sound/soc.h |  3 +++
 sound/soc/soc-pcm.c | 55 ++++++++++++++++++++++++++++++++-------------
 2 files changed, 42 insertions(+), 16 deletions(-)

diff --git a/include/sound/soc.h b/include/sound/soc.h
index 262896799826..578a8e3e08ca 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -473,6 +473,9 @@ bool snd_soc_runtime_ignore_pmdown_time(struct snd_soc_pcm_runtime *rtd);
 void snd_soc_runtime_activate(struct snd_soc_pcm_runtime *rtd, int stream);
 void snd_soc_runtime_deactivate(struct snd_soc_pcm_runtime *rtd, int stream);
 
+int snd_soc_runtime_calc_hw(struct snd_soc_pcm_runtime *rtd,
+			    struct snd_pcm_hardware *hw, int stream);
+
 int snd_soc_runtime_set_dai_fmt(struct snd_soc_pcm_runtime *rtd,
 	unsigned int dai_fmt);
 
diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 01e7bc03d92f..b53429330c8a 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -348,11 +348,18 @@ static void soc_pcm_apply_msb(struct snd_pcm_substream *substream)
 	soc_pcm_set_msb(substream, cpu_bits);
 }
 
-static void soc_pcm_init_runtime_hw(struct snd_pcm_substream *substream)
+/**
+ * snd_soc_runtime_calc_hw() - Calculate hw limits for a PCM stream
+ * @rtd: ASoC PCM runtime
+ * @hw: PCM hardware parameters (output)
+ * @stream: Direction of the PCM stream
+ *
+ * Calculates the subset of stream parameters supported by all DAIs
+ * associated with the PCM stream.
+ */
+int snd_soc_runtime_calc_hw(struct snd_soc_pcm_runtime *rtd,
+			    struct snd_pcm_hardware *hw, int stream)
 {
-	struct snd_pcm_runtime *runtime = substream->runtime;
-	struct snd_pcm_hardware *hw = &runtime->hw;
-	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct snd_soc_dai *codec_dai;
 	struct snd_soc_dai_driver *cpu_dai_drv = rtd->cpu_dai->driver;
 	struct snd_soc_dai_driver *codec_dai_drv;
@@ -364,7 +371,7 @@ static void soc_pcm_init_runtime_hw(struct snd_pcm_substream *substream)
 	u64 formats = ULLONG_MAX;
 	int i;
 
-	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+	if (stream == SNDRV_PCM_STREAM_PLAYBACK)
 		cpu_stream = &cpu_dai_drv->playback;
 	else
 		cpu_stream = &cpu_dai_drv->capture;
@@ -377,16 +384,12 @@ static void soc_pcm_init_runtime_hw(struct snd_pcm_substream *substream)
 		 * Otherwise, since the rate, channel, and format values will
 		 * zero in that case, we would have no usable settings left,
 		 * causing the resulting setup to fail.
-		 * At least one CODEC should match, otherwise we should have
-		 * bailed out on a higher level, since there would be no
-		 * CODEC to support the transfer direction in that case.
 		 */
-		if (!snd_soc_dai_stream_valid(codec_dai,
-					      substream->stream))
+		if (!snd_soc_dai_stream_valid(codec_dai, stream))
 			continue;
 
 		codec_dai_drv = codec_dai->driver;
-		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		if (stream == SNDRV_PCM_STREAM_PLAYBACK)
 			codec_stream = &codec_dai_drv->playback;
 		else
 			codec_stream = &codec_dai_drv->capture;
@@ -398,6 +401,9 @@ static void soc_pcm_init_runtime_hw(struct snd_pcm_substream *substream)
 		rates = snd_pcm_rate_mask_intersect(codec_stream->rates, rates);
 	}
 
+	if (!chan_min)
+		return -EINVAL;
+
 	/*
 	 * chan min/max cannot be enforced if there are multiple CODEC DAIs
 	 * connected to a single CPU DAI, use CPU DAI's directly and let
@@ -410,18 +416,35 @@ static void soc_pcm_init_runtime_hw(struct snd_pcm_substream *substream)
 
 	hw->channels_min = max(chan_min, cpu_stream->channels_min);
 	hw->channels_max = min(chan_max, cpu_stream->channels_max);
-	if (hw->formats)
-		hw->formats &= formats & cpu_stream->formats;
-	else
-		hw->formats = formats & cpu_stream->formats;
+	hw->formats = formats & cpu_stream->formats;
 	hw->rates = snd_pcm_rate_mask_intersect(rates, cpu_stream->rates);
 
-	snd_pcm_limit_hw_rates(runtime);
+	snd_pcm_hw_limit_rates(hw);
 
 	hw->rate_min = max(hw->rate_min, cpu_stream->rate_min);
 	hw->rate_min = max(hw->rate_min, rate_min);
 	hw->rate_max = min_not_zero(hw->rate_max, cpu_stream->rate_max);
 	hw->rate_max = min_not_zero(hw->rate_max, rate_max);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_runtime_calc_hw);
+
+static void soc_pcm_init_runtime_hw(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_hardware *hw = &substream->runtime->hw;
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	u64 formats = hw->formats;
+
+	/*
+	 * At least one CODEC should match, otherwise we should have
+	 * bailed out on a higher level, since there would be no
+	 * CODEC to support the transfer direction in that case.
+	 */
+	snd_soc_runtime_calc_hw(rtd, hw, substream->stream);
+
+	if (formats)
+		hw->formats &= formats;
 }
 
 static int soc_pcm_components_open(struct snd_pcm_substream *substream,
-- 
2.24.1