[PATCH v2 0/3] Add SoundWire port constraints into SDCA stream

[PATCH v2 0/3] Add SoundWire port constraints into SDCA stream

[Charles Keepax]

SDCA adds constraints onto the DAI based on the DisCo properties for the
Input/Output Terminal. As the SoundWire port for a Terminal can be
selected it is possible for the SoundWire port to support fewer options
than the Terminal. These patches add the SoundWire port properties into
the constraints for the DAI startup to cover these situations.

Changes since v1:
 - Move constraint allocation to DAI probe/remove
 - Use BIT macro where appropriate
 - Correct GENMASK usage
 - Add missing array indexing
 - Correct channel masking
 - Reorder the priority of SDCA properties
 - Handle the case of the word length not being specified
 - Add a static_assert to check the constraint array is large enough for
   the word length mask

Charles Keepax (3):
  ASoC: SDCA: Move DAI constraint allocation
  ASoC: SDCA: Factor out helper for creating mask of Cluster channels
  ASoC: SDCA: Add port constraints into sdca_asoc_set_constraints()

 include/sound/sdca_asoc.h            |   9 +-
 sound/soc/sdca/sdca_asoc.c           | 217 ++++++++++++++++++++-------
 sound/soc/sdca/sdca_class_function.c |   6 +-
 3 files changed, 176 insertions(+), 56 deletions(-)

-- 
2.47.3

[PATCH v2 1/3] ASoC: SDCA: Move DAI constraint allocation

[Charles Keepax]

It isn't necessary to allocate memory for constraints every time a DAI
link is opened. It is faster to allocate them once when the DAI link
is probed, update the SDCA code to do so.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---

New since v1.

This patch should fix the Sashiko complain about a potential
access after free on the first constraint if the second one
errors. Technically I think that complain wasn't really valid,
as if the open fails (when the constraints are added), then
nothing will go on to use those constraints.

However, in the process of re-assuring myself of everything I
realised it is probably just faster to alloc the constraints at
probe time rather than on each open anyway. Hence the extra patch.

 include/sound/sdca_asoc.h            |  5 +-
 sound/soc/sdca/sdca_asoc.c           | 75 +++++++++++++++++-----------
 sound/soc/sdca/sdca_class_function.c |  3 +-
 3 files changed, 52 insertions(+), 31 deletions(-)

diff --git a/include/sound/sdca_asoc.h b/include/sound/sdca_asoc.h
index 599a72f335153..236a441ec9d89 100644
--- a/include/sound/sdca_asoc.h
+++ b/include/sound/sdca_asoc.h
@@ -89,12 +89,13 @@ int sdca_asoc_populate_rate_format(struct device *dev,
 				struct sdca_entity *entity,
 				struct snd_soc_pcm_stream *stream);
 
+int sdca_asoc_alloc_constraints(struct snd_soc_dai *dai);
+int sdca_asoc_free_constraints(struct snd_soc_dai *dai);
 int sdca_asoc_set_constraints(struct device *dev, struct regmap *regmap,
 			      struct sdca_function_data *function,
 			      struct snd_pcm_substream *substream,
 			      struct snd_soc_dai *dai);
-void sdca_asoc_free_constraints(struct snd_pcm_substream *substream,
-				struct snd_soc_dai *dai);
+
 int sdca_asoc_get_port(struct device *dev, struct regmap *regmap,
 		       struct sdca_function_data *function,
 		       struct snd_soc_dai *dai);
diff --git a/sound/soc/sdca/sdca_asoc.c b/sound/soc/sdca/sdca_asoc.c
index ccc579f878ff1..b8bde56298706 100644
--- a/sound/soc/sdca/sdca_asoc.c
+++ b/sound/soc/sdca/sdca_asoc.c
@@ -1434,6 +1434,48 @@ int sdca_asoc_populate_component(struct device *dev,
 }
 EXPORT_SYMBOL_NS(sdca_asoc_populate_component, "SND_SOC_SDCA");
 
+struct sdca_asoc_constraints {
+	struct snd_pcm_hw_constraint_list channels;
+};
+
+/**
+ * sdca_asoc_alloc_constraints - allocate a constraint structure on the DAI
+ * @dai: Pointer to the ASoC DAI.
+ *
+ * Typically called from DAI probe().
+ *
+ * Return: Returns zero on success, and a negative error code on failure.
+ */
+int sdca_asoc_alloc_constraints(struct snd_soc_dai *dai)
+{
+	struct sdca_asoc_constraints *constraints;
+
+	constraints = kzalloc_obj(*constraints);
+	if (!constraints)
+		return -ENOMEM;
+
+	snd_soc_dai_set_priv(dai, constraints);
+
+	return 0;
+}
+EXPORT_SYMBOL_NS(sdca_asoc_alloc_constraints, "SND_SOC_SDCA");
+
+/**
+ * sdca_asoc_free_constraints - free constraint allocations
+ * @dai: Pointer to the ASoC DAI.
+ *
+ * Typically called from DAI remove().
+ *
+ * Return: Returns zero on success, and a negative error code on failure.
+ */
+int sdca_asoc_free_constraints(struct snd_soc_dai *dai)
+{
+	kfree(snd_soc_dai_to_priv(dai));
+
+	return 0;
+}
+EXPORT_SYMBOL_NS(sdca_asoc_free_constraints, "SND_SOC_SDCA");
+
 /**
  * sdca_asoc_set_constraints - constrain channels available on a DAI
  * @dev: Pointer to the device, used for error messages.
@@ -1455,8 +1497,8 @@ int sdca_asoc_set_constraints(struct device *dev, struct regmap *regmap,
 		 1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16,
 		17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,
 	};
+	struct sdca_asoc_constraints *constraints = snd_soc_dai_to_priv(dai);
 	struct sdca_entity *entity = &function->entities[dai->id];
-	struct snd_pcm_hw_constraint_list *constraint;
 	struct sdca_control_range *range;
 	struct sdca_control *control;
 	unsigned int channel_mask = 0;
@@ -1490,45 +1532,22 @@ int sdca_asoc_set_constraints(struct device *dev, struct regmap *regmap,
 	dev_dbg(dev, "%s: set channel constraint mask: %#x\n",
 		entity->label, channel_mask);
 
-	constraint = kzalloc_obj(*constraint);
-	if (!constraint)
-		return -ENOMEM;
-
-	constraint->count = ARRAY_SIZE(channel_list);
-	constraint->list = channel_list;
-	constraint->mask = channel_mask;
+	constraints->channels.count = ARRAY_SIZE(channel_list);
+	constraints->channels.list = channel_list;
+	constraints->channels.mask = channel_mask;
 
 	ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
 					 SNDRV_PCM_HW_PARAM_CHANNELS,
-					 constraint);
+					 &constraints->channels);
 	if (ret) {
 		dev_err(dev, "%s: failed to add constraint: %d\n", entity->label, ret);
-		kfree(constraint);
 		return ret;
 	}
 
-	snd_soc_dai_set_priv(dai, constraint);
-
 	return 0;
 }
 EXPORT_SYMBOL_NS(sdca_asoc_set_constraints, "SND_SOC_SDCA");
 
-/**
- * sdca_asoc_free_constraints - free constraint allocations
- * @substream: Pointer to the PCM substream.
- * @dai: Pointer to the ASoC DAI.
- *
- * Typically called from shutdown().
- */
-void sdca_asoc_free_constraints(struct snd_pcm_substream *substream,
-				struct snd_soc_dai *dai)
-{
-	struct snd_pcm_hw_constraint_list *constraint = snd_soc_dai_to_priv(dai);
-
-	kfree(constraint);
-}
-EXPORT_SYMBOL_NS(sdca_asoc_free_constraints, "SND_SOC_SDCA");
-
 /**
  * sdca_asoc_get_port - return SoundWire port for a DAI
  * @dev: Pointer to the device, used for error messages.
diff --git a/sound/soc/sdca/sdca_class_function.c b/sound/soc/sdca/sdca_class_function.c
index 13b70f0f0dbf7..6406c9d0f6119 100644
--- a/sound/soc/sdca/sdca_class_function.c
+++ b/sound/soc/sdca/sdca_class_function.c
@@ -184,8 +184,9 @@ static int class_function_sdw_set_stream(struct snd_soc_dai *dai, void *sdw_stre
 }
 
 static const struct snd_soc_dai_ops class_function_sdw_ops = {
+	.probe		= sdca_asoc_alloc_constraints,
+	.remove		= sdca_asoc_free_constraints,
 	.startup	= class_function_startup,
-	.shutdown	= sdca_asoc_free_constraints,
 	.set_stream	= class_function_sdw_set_stream,
 	.hw_params	= class_function_sdw_add_peripheral,
 	.hw_free	= class_function_sdw_remove_peripheral,
-- 
2.47.3

[PATCH v2 2/3] ASoC: SDCA: Factor out helper for creating mask of Cluster channels

[Charles Keepax]

Factor out the code that builds a mask of the allowed channels from the
Cluster information. This is slightly cleaner and prepares for
additional constraints to be added to sdca_asoc_set_constraints().

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---

Changes since v1:
 - Use BIT macro for the channel mask
 - Some minor knock on changes from the new first patch in the series.

 sound/soc/sdca/sdca_asoc.c | 64 +++++++++++++++++++++++---------------
 1 file changed, 39 insertions(+), 25 deletions(-)

diff --git a/sound/soc/sdca/sdca_asoc.c b/sound/soc/sdca/sdca_asoc.c
index b8bde56298706..be1b4c0075796 100644
--- a/sound/soc/sdca/sdca_asoc.c
+++ b/sound/soc/sdca/sdca_asoc.c
@@ -1476,6 +1476,37 @@ int sdca_asoc_free_constraints(struct snd_soc_dai *dai)
 }
 EXPORT_SYMBOL_NS(sdca_asoc_free_constraints, "SND_SOC_SDCA");
 
+static int get_cluster_mask(struct device *dev, struct sdca_function_data *function,
+			    struct sdca_entity *entity, unsigned int *ch_mask)
+{
+	struct sdca_control_range *range;
+	struct sdca_control *control;
+	int i;
+
+	control = sdca_selector_find_control(dev, entity, SDCA_CTL_IT_CLUSTERINDEX);
+	if (!control)
+		return -EINVAL;
+
+	range = sdca_control_find_range(dev, entity, control, SDCA_CLUSTER_NCOLS, 0);
+	if (!range)
+		return -EINVAL;
+
+	*ch_mask = 0;
+
+	for (i = 0; i < range->rows; i++) {
+		int clusterid = sdca_range(range, SDCA_CLUSTER_CLUSTERID, i);
+		struct sdca_cluster *cluster;
+
+		cluster = sdca_id_find_cluster(dev, function, clusterid);
+		if (!cluster)
+			return -ENODEV;
+
+		*ch_mask |= BIT(cluster->num_channels - 1);
+	}
+
+	return 0;
+}
+
 /**
  * sdca_asoc_set_constraints - constrain channels available on a DAI
  * @dev: Pointer to the device, used for error messages.
@@ -1499,42 +1530,25 @@ int sdca_asoc_set_constraints(struct device *dev, struct regmap *regmap,
 	};
 	struct sdca_asoc_constraints *constraints = snd_soc_dai_to_priv(dai);
 	struct sdca_entity *entity = &function->entities[dai->id];
-	struct sdca_control_range *range;
-	struct sdca_control *control;
-	unsigned int channel_mask = 0;
-	int i, ret;
+	unsigned int cluster_ch_mask;
+	int ret;
 
 	static_assert(ARRAY_SIZE(channel_list) == SDCA_MAX_CHANNEL_COUNT);
-	static_assert(sizeof(channel_mask) * BITS_PER_BYTE >= SDCA_MAX_CHANNEL_COUNT);
+	static_assert(sizeof(cluster_ch_mask) * BITS_PER_BYTE >= SDCA_MAX_CHANNEL_COUNT);
 
 	if (entity->type != SDCA_ENTITY_TYPE_IT)
 		return 0;
 
-	control = sdca_selector_find_control(dev, entity, SDCA_CTL_IT_CLUSTERINDEX);
-	if (!control)
-		return -EINVAL;
-
-	range = sdca_control_find_range(dev, entity, control, SDCA_CLUSTER_NCOLS, 0);
-	if (!range)
-		return -EINVAL;
-
-	for (i = 0; i < range->rows; i++) {
-		int clusterid = sdca_range(range, SDCA_CLUSTER_CLUSTERID, i);
-		struct sdca_cluster *cluster;
-
-		cluster = sdca_id_find_cluster(dev, function, clusterid);
-		if (!cluster)
-			return -ENODEV;
-
-		channel_mask |= (1 << (cluster->num_channels - 1));
-	}
+	ret = get_cluster_mask(dev, function, entity, &cluster_ch_mask);
+	if (ret)
+		return ret;
 
 	dev_dbg(dev, "%s: set channel constraint mask: %#x\n",
-		entity->label, channel_mask);
+		entity->label, cluster_ch_mask);
 
 	constraints->channels.count = ARRAY_SIZE(channel_list);
 	constraints->channels.list = channel_list;
-	constraints->channels.mask = channel_mask;
+	constraints->channels.mask = cluster_ch_mask;
 
 	ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
 					 SNDRV_PCM_HW_PARAM_CHANNELS,
-- 
2.47.3

[PATCH v2 3/3] ASoC: SDCA: Add port constraints into sdca_asoc_set_constraints()

[Charles Keepax]

Currently the SDCA code constrains the params based on the DisCo for
the SDCA Terminal used. However, it ignores the properties of the
SoundWire port, which in some cases may further constrain the allowed
params. Add additional constraints to apply these restrictions.

Some minor additional refactoring is required since port constraints
should be applied for both Input and Output Terminals, whereas
currently Cluster constraints are only handled for Input Terminals.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---

Change since v1:
 - Use BIT macro where appropriate
 - Correct GENMASK usage
 - Add missing array indexing
 - Correct channel masking, SDCA uses indexes not a count of channels
 - Reorder the priority of SDCA properties, it makes sense to
   consistently move from most specific to least specific
 - Handle the case of the word length not being specified, as it is
   optional the SDCA specification
 - Add a static_assert to check the constraint array is large enough for
   the word length mask
 - Some knock on changes from the new first patch in the series

 include/sound/sdca_asoc.h            |   4 +-
 sound/soc/sdca/sdca_asoc.c           | 108 +++++++++++++++++++++++----
 sound/soc/sdca/sdca_class_function.c |   3 +-
 3 files changed, 100 insertions(+), 15 deletions(-)

diff --git a/include/sound/sdca_asoc.h b/include/sound/sdca_asoc.h
index 236a441ec9d89..26740f69f2bee 100644
--- a/include/sound/sdca_asoc.h
+++ b/include/sound/sdca_asoc.h
@@ -12,6 +12,7 @@
 
 struct device;
 struct regmap;
+struct sdw_slave;
 struct sdca_function_data;
 struct sdca_pde_delay;
 struct snd_ctl_elem_value;
@@ -91,7 +92,8 @@ int sdca_asoc_populate_rate_format(struct device *dev,
 
 int sdca_asoc_alloc_constraints(struct snd_soc_dai *dai);
 int sdca_asoc_free_constraints(struct snd_soc_dai *dai);
-int sdca_asoc_set_constraints(struct device *dev, struct regmap *regmap,
+int sdca_asoc_set_constraints(struct device *dev, struct sdw_slave *sdw,
+			      struct regmap *regmap,
 			      struct sdca_function_data *function,
 			      struct snd_pcm_substream *substream,
 			      struct snd_soc_dai *dai);
diff --git a/sound/soc/sdca/sdca_asoc.c b/sound/soc/sdca/sdca_asoc.c
index be1b4c0075796..d1b40c6ccae2b 100644
--- a/sound/soc/sdca/sdca_asoc.c
+++ b/sound/soc/sdca/sdca_asoc.c
@@ -13,11 +13,13 @@
 #include <linux/delay.h>
 #include <linux/dev_printk.h>
 #include <linux/device.h>
+#include <linux/limits.h>
 #include <linux/minmax.h>
 #include <linux/module.h>
 #include <linux/overflow.h>
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
+#include <linux/soundwire/sdw.h>
 #include <linux/soundwire/sdw_registers.h>
 #include <linux/string_helpers.h>
 #include <linux/types.h>
@@ -1435,6 +1437,7 @@ int sdca_asoc_populate_component(struct device *dev,
 EXPORT_SYMBOL_NS(sdca_asoc_populate_component, "SND_SOC_SDCA");
 
 struct sdca_asoc_constraints {
+	struct snd_pcm_hw_constraint_list width;
 	struct snd_pcm_hw_constraint_list channels;
 };
 
@@ -1507,9 +1510,57 @@ static int get_cluster_mask(struct device *dev, struct sdca_function_data *funct
 	return 0;
 }
 
+static int get_port_masks(struct sdw_slave *sdw, unsigned int port,
+			  struct snd_pcm_substream *substream,
+			  unsigned int *word_mask, unsigned int *ch_mask)
+{
+	struct sdw_dpn_prop *prop;
+	unsigned int nprop;
+	int i, j;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		prop = sdw->prop.sink_dpn_prop;
+		nprop = hweight32(sdw->prop.sink_ports);
+	} else {
+		prop = sdw->prop.src_dpn_prop;
+		nprop = hweight32(sdw->prop.source_ports);
+	}
+
+	*word_mask = 0;
+	*ch_mask = 0;
+
+	for (i = 0; i < nprop; i++) {
+		if (prop[i].num != port)
+			continue;
+
+		if (prop[i].num_words) {
+			for (j = 0; j < prop[i].num_words; j++)
+				*word_mask |= BIT(prop[i].words[j] - 1);
+		} else {
+			*word_mask = GENMASK(MIN(31, prop[i].max_word - 1),
+					     MAX(1, prop[i].min_word) - 1);
+		}
+
+		/* Only handle the number of channels for constraints. */
+		if (prop[i].num_ch_combinations) {
+			for (j = 0; j < prop[i].num_ch_combinations; j++)
+				*ch_mask |= BIT(hweight32(prop[i].ch_combinations[j]) - 1);
+		} else if (prop[i].num_channels) {
+			*ch_mask = GENMASK(prop[i].num_channels - 1, 0);
+		} else {
+			*ch_mask = GENMASK(prop[i].max_ch - prop[i].min_ch, 0);
+		}
+
+		return 0;
+	}
+
+	return -ENODEV;
+}
+
 /**
  * sdca_asoc_set_constraints - constrain channels available on a DAI
  * @dev: Pointer to the device, used for error messages.
+ * @sdw: Pointer to the SoundWire peripheral device.
  * @regmap: Pointer to the Function register map.
  * @function: Pointer to the Function information.
  * @substream: Pointer to the PCM substream.
@@ -1519,42 +1570,73 @@ static int get_cluster_mask(struct device *dev, struct sdca_function_data *funct
  *
  * Return: Returns zero on success, and a negative error code on failure.
  */
-int sdca_asoc_set_constraints(struct device *dev, struct regmap *regmap,
+int sdca_asoc_set_constraints(struct device *dev, struct sdw_slave *sdw,
+			      struct regmap *regmap,
 			      struct sdca_function_data *function,
 			      struct snd_pcm_substream *substream,
 			      struct snd_soc_dai *dai)
 {
-	static const unsigned int channel_list[] = {
+	static const unsigned int constraint_list[] = {
 		 1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16,
 		17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,
 	};
 	struct sdca_asoc_constraints *constraints = snd_soc_dai_to_priv(dai);
 	struct sdca_entity *entity = &function->entities[dai->id];
+	unsigned int port_ch_mask, port_width_mask;
 	unsigned int cluster_ch_mask;
+	int port;
 	int ret;
 
-	static_assert(ARRAY_SIZE(channel_list) == SDCA_MAX_CHANNEL_COUNT);
+	static_assert(ARRAY_SIZE(constraint_list) <= sizeof(port_width_mask) * BITS_PER_BYTE);
+	static_assert(ARRAY_SIZE(constraint_list) == SDCA_MAX_CHANNEL_COUNT);
 	static_assert(sizeof(cluster_ch_mask) * BITS_PER_BYTE >= SDCA_MAX_CHANNEL_COUNT);
 
-	if (entity->type != SDCA_ENTITY_TYPE_IT)
-		return 0;
+	/* FIXME: Currently only a single unshared port is supported */
+	port = sdca_asoc_get_port(dev, regmap, function, dai);
+	if (port < 0)
+		return port;
 
-	ret = get_cluster_mask(dev, function, entity, &cluster_ch_mask);
-	if (ret)
+	ret = get_port_masks(sdw, port, substream, &port_width_mask, &port_ch_mask);
+	if (ret < 0) {
+		dev_err(dev, "%s: no properties for port %d\n", entity->label, port);
 		return ret;
+	}
+
+	/* FIXME: OTs should inherit cluster information */
+	if (entity->type == SDCA_ENTITY_TYPE_IT) {
+		ret = get_cluster_mask(dev, function, entity, &cluster_ch_mask);
+		if (ret)
+			return ret;
+	} else {
+		cluster_ch_mask = UINT_MAX;
+	}
+
+	constraints->channels.count = ARRAY_SIZE(constraint_list);
+	constraints->channels.list = constraint_list;
+	constraints->channels.mask = cluster_ch_mask & port_ch_mask;
 
-	dev_dbg(dev, "%s: set channel constraint mask: %#x\n",
-		entity->label, cluster_ch_mask);
+	constraints->width.count = ARRAY_SIZE(constraint_list);
+	constraints->width.list = constraint_list;
+	constraints->width.mask = port_width_mask;
 
-	constraints->channels.count = ARRAY_SIZE(channel_list);
-	constraints->channels.list = channel_list;
-	constraints->channels.mask = cluster_ch_mask;
+	dev_dbg(dev, "%s: set constraint masks, channel: %#x, width: %#x\n",
+		entity->label, constraints->channels.mask, constraints->width.mask);
 
 	ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
 					 SNDRV_PCM_HW_PARAM_CHANNELS,
 					 &constraints->channels);
 	if (ret) {
-		dev_err(dev, "%s: failed to add constraint: %d\n", entity->label, ret);
+		dev_err(dev, "%s: failed to add channel constraint: %d\n",
+			entity->label, ret);
+		return ret;
+	}
+
+	ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
+					 SNDRV_PCM_HW_PARAM_SAMPLE_BITS,
+					 &constraints->width);
+	if (ret) {
+		dev_err(dev, "%s: failed to add word constraint: %d\n",
+			entity->label, ret);
 		return ret;
 	}
 
diff --git a/sound/soc/sdca/sdca_class_function.c b/sound/soc/sdca/sdca_class_function.c
index 6406c9d0f6119..abccc63640c68 100644
--- a/sound/soc/sdca/sdca_class_function.c
+++ b/sound/soc/sdca/sdca_class_function.c
@@ -121,8 +121,9 @@ static int class_function_startup(struct snd_pcm_substream *substream,
 				  struct snd_soc_dai *dai)
 {
 	struct class_function_drv *drv = snd_soc_component_get_drvdata(dai->component);
+	struct sdw_slave *sdw = dev_to_sdw_dev(drv->dev->parent);
 
-	return sdca_asoc_set_constraints(drv->dev, drv->regmap, drv->function,
+	return sdca_asoc_set_constraints(drv->dev, sdw, drv->regmap, drv->function,
 					 substream, dai);
 }
 
-- 
2.47.3

Re: [PATCH v2 3/3] ASoC: SDCA: Add port constraints into sdca_asoc_set_constraints()

[Charles Keepax]

On Fri, Nov 06, 2026 at 03:09:26PM +0000, Charles Keepax wrote:
> Currently the SDCA code constrains the params based on the DisCo for
> the SDCA Terminal used. However, it ignores the properties of the
> SoundWire port, which in some cases may further constrain the allowed
> params. Add additional constraints to apply these restrictions.
> 
> Some minor additional refactoring is required since port constraints
> should be applied for both Input and Output Terminals, whereas
> currently Cluster constraints are only handled for Input Terminals.
> 
> Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
> ---
> +	constraints->channels.count = ARRAY_SIZE(constraint_list);
> +	constraints->channels.list = constraint_list;
> +	constraints->channels.mask = cluster_ch_mask & port_ch_mask;

Sashiko is still concerned about if these two masks don't
overlap, resulting in a mask of 0 which allows all the options. I
think that seems valid so will add a check to fail here if there
is no overlap.

> +	ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
> +					 SNDRV_PCM_HW_PARAM_SAMPLE_BITS,
> +					 &constraints->width);

Sashiko is also concerned that SAMPLE_BITS is actually the
physical width (ie. memory size) of the sample which feels
sub-optimally named but does look like it checks out. So I
think we have to switch this to using HW_PARAM_FORMAT, but
will think it over.

Will do a spin for these updates early next week, unless I
hear any more by then.

Thanks,
Charles