[PATCH v7 00/10] soundwire: Add multi link support

[PATCH v7 00/10] soundwire: Add multi link support

[Shreyas NC]

Currently, in the SoundWire subsystem, the concept of stream is limited
to a Master and one or more Slaves(Codecs). This series aims to add
support for multiple Master(s) sharing the same reference clock and
synchronized in the hardware.

This patch series adds:
 - Fix to avoid duplicate stream state assignment
 - Avoid incorrect stream release after configuring Master
 - Fix to avoid bus lock acquired twice
 - Helpers to lock bus instances part of the stream
 - Boiler plate conversion of code to support a list of Master runtime
 - Support multi link bank switch to support synchronization between
   multiple masters
 - Add Intel platform ops for pre/post bank switch

Additionally, as suggested by Vinod, the generic fixes are arranged
at the top of the series followed by the Documentation patch for
multi link support and then the multi link patches.

changes in v7:
 - Fix the git bisect issue pointed by Pierre. Now, the initialization
   of the m_rt_count and its modification/usage is split into 2 patches.
   While the declaration and initialization is in one patch,
   modification of the refcount and usage is in the multilink bankswitch
   patch.
 - Re-arrange the patches as suggested by Vinod

changes in v6:
 - Add patch to fix acquiring bus lock twice during master release
 - In sdw_stream_add_master(), perform multi link check at start of
   function as suggested by Pierre
 - Minor comment fixes

Sanyog Kale (3):
  soundwire: Fix acquiring bus lock twice during master release
  Documentation: soundwire: Add documentation for multi link
  soundwire: Add support to lock across bus instances

Shreyas NC (6):
  soundwire: Fix duplicate stream state assignment
  soundwire: Fix incorrect exit after configuring stream
  soundwire: Initialize completion for defer messages
  soundwire: keep track of Masters in a stream
  soundwire: Add support for multi link bank switch
  soundwire: intel: Add pre/post bank switch ops

Vinod Koul (1):
  soundwire: Handle multiple master instances in a stream

 Documentation/driver-api/soundwire/stream.rst |  28 ++
 drivers/soundwire/bus.c                       |   6 +
 drivers/soundwire/bus.h                       |   4 +
 drivers/soundwire/intel.c                     |  65 ++++
 drivers/soundwire/stream.c                    | 511 +++++++++++++++++++-------
 include/linux/soundwire/sdw.h                 |  12 +-
 6 files changed, 489 insertions(+), 137 deletions(-)

-- 
2.7.4

[PATCH v7 01/10] soundwire: Fix duplicate stream state assignment

[Shreyas NC]

For a SoundWire stream it is expected that a Slave is added to the
stream before Master is added.

So, move the stream state to CONFIGURED after the first Slave is
added and remove the stream state assignment for Master add.
Along with these changes, add additional comments to explain the same.

Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
---
 drivers/soundwire/stream.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
index 8974a0f..e6ee4ba 100644
--- a/drivers/soundwire/stream.c
+++ b/drivers/soundwire/stream.c
@@ -1123,8 +1123,6 @@ int sdw_stream_add_master(struct sdw_bus *bus,
 	if (ret)
 		goto stream_error;
 
-	stream->state = SDW_STREAM_CONFIGURED;
-
 stream_error:
 	sdw_release_master_stream(stream);
 error:
@@ -1141,6 +1139,10 @@ EXPORT_SYMBOL(sdw_stream_add_master);
  * @stream: SoundWire stream
  * @port_config: Port configuration for audio stream
  * @num_ports: Number of ports
+ *
+ * It is expected that Slave is added before adding Master
+ * to the Stream.
+ *
  */
 int sdw_stream_add_slave(struct sdw_slave *slave,
 		struct sdw_stream_config *stream_config,
@@ -1186,6 +1188,12 @@ int sdw_stream_add_slave(struct sdw_slave *slave,
 	if (ret)
 		goto stream_error;
 
+	/*
+	 * Change stream state to CONFIGURED on first Slave add.
+	 * Bus is not aware of number of Slave(s) in a stream at this
+	 * point so cannot depend on all Slave(s) to be added in order to
+	 * change stream state to CONFIGURED.
+	 */
 	stream->state = SDW_STREAM_CONFIGURED;
 	goto error;
 
-- 
2.7.4

[PATCH v7 02/10] soundwire: Fix incorrect exit after configuring stream

[Shreyas NC]

In sdw_stream_add_master() after the Master ports are configured,
the stream is released incorrectly.

So, fix it by avoiding stream release after configuring the Master
for the stream.
While at it, rename the label appropriately.

Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
---
 drivers/soundwire/stream.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
index e6ee4ba..eaaa180 100644
--- a/drivers/soundwire/stream.c
+++ b/drivers/soundwire/stream.c
@@ -1112,7 +1112,7 @@ int sdw_stream_add_master(struct sdw_bus *bus,
 				"Master runtime config failed for stream:%s",
 				stream->name);
 		ret = -ENOMEM;
-		goto error;
+		goto unlock;
 	}
 
 	ret = sdw_config_stream(bus->dev, stream, stream_config, false);
@@ -1123,9 +1123,11 @@ int sdw_stream_add_master(struct sdw_bus *bus,
 	if (ret)
 		goto stream_error;
 
+	goto unlock;
+
 stream_error:
 	sdw_release_master_stream(stream);
-error:
+unlock:
 	mutex_unlock(&bus->bus_lock);
 	return ret;
 }
-- 
2.7.4

[PATCH v7 03/10] soundwire: Fix acquiring bus lock twice during master release

[Shreyas NC]

From: Sanyog Kale <sanyog.r.kale@intel.com>

As part of sdw_stream_remove_master(), sdw_stream_remove_slave() is called
which results in bus lock being acquired twice.

So, fix it by performing specific Slave remove operations in
sdw_release_master_stream() instead of calling sdw_stream_remove_slave().

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
---
 drivers/soundwire/stream.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
index eaaa180..28d4147 100644
--- a/drivers/soundwire/stream.c
+++ b/drivers/soundwire/stream.c
@@ -899,9 +899,10 @@ static void sdw_release_master_stream(struct sdw_stream_runtime *stream)
 	struct sdw_master_runtime *m_rt = stream->m_rt;
 	struct sdw_slave_runtime *s_rt, *_s_rt;
 
-	list_for_each_entry_safe(s_rt, _s_rt,
-			&m_rt->slave_rt_list, m_rt_node)
-		sdw_stream_remove_slave(s_rt->slave, stream);
+	list_for_each_entry_safe(s_rt, _s_rt, &m_rt->slave_rt_list, m_rt_node) {
+		sdw_slave_port_release(s_rt->slave->bus, s_rt->slave, stream);
+		sdw_release_slave_stream(s_rt->slave, stream);
+	}
 
 	list_del(&m_rt->bus_node);
 }
-- 
2.7.4

[PATCH v7 04/10] Documentation: soundwire: Add documentation for multi link

[Shreyas NC]

From: Sanyog Kale <sanyog.r.kale@intel.com>

Add example and documentation to describe multi link streams

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
---
 Documentation/driver-api/soundwire/stream.rst | 28 +++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/Documentation/driver-api/soundwire/stream.rst b/Documentation/driver-api/soundwire/stream.rst
index 29121aa..19482ee 100644
--- a/Documentation/driver-api/soundwire/stream.rst
+++ b/Documentation/driver-api/soundwire/stream.rst
@@ -101,6 +101,34 @@ interface. ::
 	+--------------------+                             |                |
 							   +----------------+
 
+Example 5: Stereo Stream with L and R channel is rendered by 2 Masters, each
+rendering one channel, and is received by two different Slaves, each
+receiving one channel. Both Masters and both Slaves are using single port. ::
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       1       |                                  |       1       |
+	|               |                     Data Signal  |               |
+	|       L       +----------------------------------+       L       |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       2       |                                  |       2       |
+	|               |                     Data Signal  |               |
+	|       R       +----------------------------------+       R       |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+Note: In multi-link cases like above, to lock, one would acquire a global
+lock and then go on locking bus instances. But, in this case the caller
+framework(ASoC DPCM) guarantees that stream operations on a card are
+always serialized. So, there is no race condition and hence no need for
+global lock.
+
 SoundWire Stream Management flow
 ================================
 
-- 
2.7.4

[PATCH v7 05/10] soundwire: Initialize completion for defer messages

[Shreyas NC]

Deferred messages are async messages used to synchronize
transitions mostly while doing a bank switch on multi links.
On successful transitions these messages are marked complete
and thereby confirming that all the buses performed bank switch
successfully.

So, initialize the completion structure for the same.

Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
---
 drivers/soundwire/bus.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index dcc0ff9..dbabd5e 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -175,6 +175,7 @@ static inline int do_transfer_defer(struct sdw_bus *bus,
 
 	defer->msg = msg;
 	defer->length = msg->len;
+	init_completion(&defer->complete);
 
 	for (i = 0; i <= retry; i++) {
 		resp = bus->ops->xfer_msg_defer(bus, msg, defer);
-- 
2.7.4

[PATCH v7 06/10] soundwire: Add support to lock across bus instances

[Shreyas NC]

From: Sanyog Kale <sanyog.r.kale@intel.com>

Currently, the stream concept is limited to single Master and one
or more Codecs.

This patch extends the concept to support multiple Master(s)
sharing the same reference clock and synchronized in the hardware.
Modify sdw_stream_runtime to support a list of sdw_master_runtime
for the same. The existing reference to a single m_rt is removed
in the next patch.

Typically to lock, one would acquire a global lock and then lock
bus instances. In this case, the caller framework(ASoC DPCM)
guarantees that stream operations on a card are always serialized.
So, there is no race condition and hence no need for global lock.

Bus lock(s) are acquired to reconfigure the bus while the stream
is set-up.
So, we add sdw_acquire_bus_lock()/sdw_release_bus_lock() APIs which
are used only to reconfigure the bus.

Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
---
 drivers/soundwire/bus.h       |  2 ++
 drivers/soundwire/stream.c    | 43 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/soundwire/sdw.h |  4 ++++
 3 files changed, 49 insertions(+)

diff --git a/drivers/soundwire/bus.h b/drivers/soundwire/bus.h
index 3b15c4e..b6cfbdf 100644
--- a/drivers/soundwire/bus.h
+++ b/drivers/soundwire/bus.h
@@ -99,6 +99,7 @@ struct sdw_slave_runtime {
  * this stream, can be zero.
  * @slave_rt_list: Slave runtime list
  * @port_list: List of Master Ports configured for this stream, can be zero.
+ * @stream_node: sdw_stream_runtime master_list node
  * @bus_node: sdw_bus m_rt_list node
  */
 struct sdw_master_runtime {
@@ -108,6 +109,7 @@ struct sdw_master_runtime {
 	unsigned int ch_count;
 	struct list_head slave_rt_list;
 	struct list_head port_list;
+	struct list_head stream_node;
 	struct list_head bus_node;
 };
 
diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
index 28d4147..c6e497d 100644
--- a/drivers/soundwire/stream.c
+++ b/drivers/soundwire/stream.c
@@ -747,6 +747,7 @@ struct sdw_stream_runtime *sdw_alloc_stream(char *stream_name)
 		return NULL;
 
 	stream->name = stream_name;
+	INIT_LIST_HEAD(&stream->master_list);
 	stream->state = SDW_STREAM_ALLOCATED;
 
 	return stream;
@@ -1245,6 +1246,48 @@ struct sdw_dpn_prop *sdw_get_slave_dpn_prop(struct sdw_slave *slave,
 	return NULL;
 }
 
+/**
+ * sdw_acquire_bus_lock: Acquire bus lock for all Master runtime(s)
+ *
+ * @stream: SoundWire stream
+ *
+ * Acquire bus_lock for each of the master runtime(m_rt) part of this
+ * stream to reconfigure the bus.
+ * NOTE: This function is called from SoundWire stream ops and is
+ * expected that a global lock is held before acquiring bus_lock.
+ */
+static void sdw_acquire_bus_lock(struct sdw_stream_runtime *stream)
+{
+	struct sdw_master_runtime *m_rt = NULL;
+	struct sdw_bus *bus = NULL;
+
+	/* Iterate for all Master(s) in Master list */
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+
+		mutex_lock(&bus->bus_lock);
+	}
+}
+
+/**
+ * sdw_release_bus_lock: Release bus lock for all Master runtime(s)
+ *
+ * @stream: SoundWire stream
+ *
+ * Release the previously held bus_lock after reconfiguring the bus.
+ */
+static void sdw_release_bus_lock(struct sdw_stream_runtime *stream)
+{
+	struct sdw_master_runtime *m_rt = NULL;
+	struct sdw_bus *bus = NULL;
+
+	/* Iterate for all Master(s) in Master list */
+	list_for_each_entry_reverse(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		mutex_unlock(&bus->bus_lock);
+	}
+}
+
 static int _sdw_prepare_stream(struct sdw_stream_runtime *stream)
 {
 	struct sdw_master_runtime *m_rt = stream->m_rt;
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 962971e..ccd8dcdf 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -769,6 +769,9 @@ struct sdw_stream_params {
  * @state: Current state of the stream
  * @type: Stream type PCM or PDM
  * @m_rt: Master runtime
+ * @master_list: List of Master runtime(s) in this stream.
+ * master_list can contain only one m_rt per Master instance
+ * for a stream
  */
 struct sdw_stream_runtime {
 	char *name;
@@ -776,6 +779,7 @@ struct sdw_stream_runtime {
 	enum sdw_stream_state state;
 	enum sdw_stream_type type;
 	struct sdw_master_runtime *m_rt;
+	struct list_head master_list;
 };
 
 struct sdw_stream_runtime *sdw_alloc_stream(char *stream_name);
-- 
2.7.4

[PATCH v7 07/10] soundwire: Handle multiple master instances in a stream

[Shreyas NC]

From: Vinod Koul <vkoul@kernel.org>

For each SoundWire stream operation, we need to parse master
list and operate upon all master runtime.

This is a preparatory patch to do the boilerplate conversion
of stream handling from single master runtime to handle a
list of master runtime. The code to support bank switch for
multiple master instances is added in the next patch.

Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
---
 drivers/soundwire/stream.c    | 311 +++++++++++++++++++++++++-----------------
 include/linux/soundwire/sdw.h |   2 -
 2 files changed, 188 insertions(+), 125 deletions(-)

diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
index c6e497d..0d04d84 100644
--- a/drivers/soundwire/stream.c
+++ b/drivers/soundwire/stream.c
@@ -681,35 +681,45 @@ static int sdw_bank_switch(struct sdw_bus *bus)
 
 static int do_bank_switch(struct sdw_stream_runtime *stream)
 {
-	struct sdw_master_runtime *m_rt = stream->m_rt;
+	struct sdw_master_runtime *m_rt = NULL;
 	const struct sdw_master_ops *ops;
-	struct sdw_bus *bus = m_rt->bus;
+	struct sdw_bus *bus = NULL;
 	int ret = 0;
 
-	ops = bus->ops;
 
-	/* Pre-bank switch */
-	if (ops->pre_bank_switch) {
-		ret = ops->pre_bank_switch(bus);
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		ops = bus->ops;
+
+		/* Pre-bank switch */
+		if (ops->pre_bank_switch) {
+			ret = ops->pre_bank_switch(bus);
+			if (ret < 0) {
+				dev_err(bus->dev,
+					"Pre bank switch op failed: %d", ret);
+				return ret;
+			}
+		}
+
+		/* Bank switch */
+		ret = sdw_bank_switch(bus);
 		if (ret < 0) {
-			dev_err(bus->dev, "Pre bank switch op failed: %d", ret);
+			dev_err(bus->dev, "Bank switch failed: %d", ret);
 			return ret;
 		}
 	}
 
-	/* Bank switch */
-	ret = sdw_bank_switch(bus);
-	if (ret < 0) {
-		dev_err(bus->dev, "Bank switch failed: %d", ret);
-		return ret;
-	}
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		ops = bus->ops;
 
-	/* Post-bank switch */
-	if (ops->post_bank_switch) {
-		ret = ops->post_bank_switch(bus);
-		if (ret < 0) {
-			dev_err(bus->dev,
+		/* Post-bank switch */
+		if (ops->post_bank_switch) {
+			ret = ops->post_bank_switch(bus);
+			if (ret < 0) {
+				dev_err(bus->dev,
 					"Post bank switch op failed: %d", ret);
+			}
 		}
 	}
 
@@ -754,6 +764,21 @@ struct sdw_stream_runtime *sdw_alloc_stream(char *stream_name)
 }
 EXPORT_SYMBOL(sdw_alloc_stream);
 
+static struct sdw_master_runtime
+*sdw_find_master_rt(struct sdw_bus *bus,
+			struct sdw_stream_runtime *stream)
+{
+	struct sdw_master_runtime *m_rt = NULL;
+
+	/* Retrieve Bus handle if already available */
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		if (m_rt->bus == bus)
+			return m_rt;
+	}
+
+	return NULL;
+}
+
 /**
  * sdw_alloc_master_rt() - Allocates and initialize Master runtime handle
  *
@@ -770,12 +795,11 @@ static struct sdw_master_runtime
 {
 	struct sdw_master_runtime *m_rt;
 
-	m_rt = stream->m_rt;
-
 	/*
 	 * check if Master is already allocated (as a result of Slave adding
 	 * it first), if so skip allocation and go to configure
 	 */
+	m_rt = sdw_find_master_rt(bus, stream);
 	if (m_rt)
 		goto stream_config;
 
@@ -786,7 +810,7 @@ static struct sdw_master_runtime
 	/* Initialization of Master runtime handle */
 	INIT_LIST_HEAD(&m_rt->port_list);
 	INIT_LIST_HEAD(&m_rt->slave_rt_list);
-	stream->m_rt = m_rt;
+	list_add_tail(&m_rt->stream_node, &stream->master_list);
 
 	list_add_tail(&m_rt->bus_node, &bus->m_rt_list);
 
@@ -844,17 +868,21 @@ static void sdw_slave_port_release(struct sdw_bus *bus,
 			struct sdw_stream_runtime *stream)
 {
 	struct sdw_port_runtime *p_rt, *_p_rt;
-	struct sdw_master_runtime *m_rt = stream->m_rt;
+	struct sdw_master_runtime *m_rt;
 	struct sdw_slave_runtime *s_rt;
 
-	list_for_each_entry(s_rt, &m_rt->slave_rt_list, m_rt_node) {
-		if (s_rt->slave != slave)
-			continue;
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		list_for_each_entry(s_rt, &m_rt->slave_rt_list, m_rt_node) {
 
-		list_for_each_entry_safe(p_rt, _p_rt,
-				&s_rt->port_list, port_node) {
-			list_del(&p_rt->port_node);
-			kfree(p_rt);
+			if (s_rt->slave != slave)
+				continue;
+
+			list_for_each_entry_safe(p_rt, _p_rt,
+					&s_rt->port_list, port_node) {
+
+				list_del(&p_rt->port_node);
+				kfree(p_rt);
+			}
 		}
 	}
 }
@@ -871,16 +899,18 @@ static void sdw_release_slave_stream(struct sdw_slave *slave,
 			struct sdw_stream_runtime *stream)
 {
 	struct sdw_slave_runtime *s_rt, *_s_rt;
-	struct sdw_master_runtime *m_rt = stream->m_rt;
-
-	/* Retrieve Slave runtime handle */
-	list_for_each_entry_safe(s_rt, _s_rt,
-			&m_rt->slave_rt_list, m_rt_node) {
+	struct sdw_master_runtime *m_rt;
 
-		if (s_rt->slave == slave) {
-			list_del(&s_rt->m_rt_node);
-			kfree(s_rt);
-			return;
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		/* Retrieve Slave runtime handle */
+		list_for_each_entry_safe(s_rt, _s_rt,
+					&m_rt->slave_rt_list, m_rt_node) {
+
+			if (s_rt->slave == slave) {
+				list_del(&s_rt->m_rt_node);
+				kfree(s_rt);
+				return;
+			}
 		}
 	}
 }
@@ -888,6 +918,7 @@ static void sdw_release_slave_stream(struct sdw_slave *slave,
 /**
  * sdw_release_master_stream() - Free Master runtime handle
  *
+ * @m_rt: Master runtime node
  * @stream: Stream runtime handle.
  *
  * This function is to be called with bus_lock held
@@ -895,9 +926,9 @@ static void sdw_release_slave_stream(struct sdw_slave *slave,
  * handle. If this is called first then sdw_release_slave_stream() will have
  * no effect as Slave(s) runtime handle would already be freed up.
  */
-static void sdw_release_master_stream(struct sdw_stream_runtime *stream)
+static void sdw_release_master_stream(struct sdw_master_runtime *m_rt,
+			struct sdw_stream_runtime *stream)
 {
-	struct sdw_master_runtime *m_rt = stream->m_rt;
 	struct sdw_slave_runtime *s_rt, *_s_rt;
 
 	list_for_each_entry_safe(s_rt, _s_rt, &m_rt->slave_rt_list, m_rt_node) {
@@ -905,7 +936,9 @@ static void sdw_release_master_stream(struct sdw_stream_runtime *stream)
 		sdw_release_slave_stream(s_rt->slave, stream);
 	}
 
+	list_del(&m_rt->stream_node);
 	list_del(&m_rt->bus_node);
+	kfree(m_rt);
 }
 
 /**
@@ -919,13 +952,22 @@ static void sdw_release_master_stream(struct sdw_stream_runtime *stream)
 int sdw_stream_remove_master(struct sdw_bus *bus,
 		struct sdw_stream_runtime *stream)
 {
+	struct sdw_master_runtime *m_rt, *_m_rt;
+
 	mutex_lock(&bus->bus_lock);
 
-	sdw_release_master_stream(stream);
-	sdw_master_port_release(bus, stream->m_rt);
-	stream->state = SDW_STREAM_RELEASED;
-	kfree(stream->m_rt);
-	stream->m_rt = NULL;
+	list_for_each_entry_safe(m_rt, _m_rt,
+			&stream->master_list, stream_node) {
+
+		if (m_rt->bus != bus)
+			continue;
+
+		sdw_master_port_release(bus, m_rt);
+		sdw_release_master_stream(m_rt, stream);
+	}
+
+	if (list_empty(&stream->master_list))
+		stream->state = SDW_STREAM_RELEASED;
 
 	mutex_unlock(&bus->bus_lock);
 
@@ -1128,7 +1170,7 @@ int sdw_stream_add_master(struct sdw_bus *bus,
 	goto unlock;
 
 stream_error:
-	sdw_release_master_stream(stream);
+	sdw_release_master_stream(m_rt, stream);
 unlock:
 	mutex_unlock(&bus->bus_lock);
 	return ret;
@@ -1206,7 +1248,7 @@ int sdw_stream_add_slave(struct sdw_slave *slave,
 	 * we hit error so cleanup the stream, release all Slave(s) and
 	 * Master runtime
 	 */
-	sdw_release_master_stream(stream);
+	sdw_release_master_stream(m_rt, stream);
 error:
 	mutex_unlock(&slave->bus->bus_lock);
 	return ret;
@@ -1275,6 +1317,8 @@ static void sdw_acquire_bus_lock(struct sdw_stream_runtime *stream)
  * @stream: SoundWire stream
  *
  * Release the previously held bus_lock after reconfiguring the bus.
+ * NOTE: This function is called from SoundWire stream ops and is
+ * expected that a global lock is held before releasing bus_lock.
  */
 static void sdw_release_bus_lock(struct sdw_stream_runtime *stream)
 {
@@ -1290,31 +1334,36 @@ static void sdw_release_bus_lock(struct sdw_stream_runtime *stream)
 
 static int _sdw_prepare_stream(struct sdw_stream_runtime *stream)
 {
-	struct sdw_master_runtime *m_rt = stream->m_rt;
-	struct sdw_bus *bus = m_rt->bus;
+	struct sdw_master_runtime *m_rt = NULL;
+	struct sdw_bus *bus = NULL;
 	struct sdw_master_prop *prop = NULL;
 	struct sdw_bus_params params;
 	int ret;
 
-	prop = &bus->prop;
-	memcpy(&params, &bus->params, sizeof(params));
+	/* Prepare  Master(s) and Slave(s) port(s) associated with stream */
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		prop = &bus->prop;
+		memcpy(&params, &bus->params, sizeof(params));
 
-	/* TODO: Support Asynchronous mode */
-	if ((prop->max_freq % stream->params.rate) != 0) {
-		dev_err(bus->dev, "Async mode not supported");
-		return -EINVAL;
-	}
+		/* TODO: Support Asynchronous mode */
+		if ((prop->max_freq % stream->params.rate) != 0) {
+			dev_err(bus->dev, "Async mode not supported");
+			return -EINVAL;
+		}
 
-	/* Increment cumulative bus bandwidth */
-	/* TODO: Update this during Device-Device support */
-	bus->params.bandwidth += m_rt->stream->params.rate *
-		m_rt->ch_count * m_rt->stream->params.bps;
+		/* Increment cumulative bus bandwidth */
+		/* TODO: Update this during Device-Device support */
+		bus->params.bandwidth += m_rt->stream->params.rate *
+			m_rt->ch_count * m_rt->stream->params.bps;
+
+		/* Program params */
+		ret = sdw_program_params(bus);
+		if (ret < 0) {
+			dev_err(bus->dev, "Program params failed: %d", ret);
+			goto restore_params;
+		}
 
-	/* Program params */
-	ret = sdw_program_params(bus);
-	if (ret < 0) {
-		dev_err(bus->dev, "Program params failed: %d", ret);
-		goto restore_params;
 	}
 
 	ret = do_bank_switch(stream);
@@ -1323,12 +1372,16 @@ static int _sdw_prepare_stream(struct sdw_stream_runtime *stream)
 		goto restore_params;
 	}
 
-	/* Prepare port(s) on the new clock configuration */
-	ret = sdw_prep_deprep_ports(m_rt, true);
-	if (ret < 0) {
-		dev_err(bus->dev, "Prepare port(s) failed ret = %d",
-				ret);
-		return ret;
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+
+		/* Prepare port(s) on the new clock configuration */
+		ret = sdw_prep_deprep_ports(m_rt, true);
+		if (ret < 0) {
+			dev_err(bus->dev, "Prepare port(s) failed ret = %d",
+					ret);
+			return ret;
+		}
 	}
 
 	stream->state = SDW_STREAM_PREPARED;
@@ -1356,35 +1409,40 @@ int sdw_prepare_stream(struct sdw_stream_runtime *stream)
 		return -EINVAL;
 	}
 
-	mutex_lock(&stream->m_rt->bus->bus_lock);
+	sdw_acquire_bus_lock(stream);
 
 	ret = _sdw_prepare_stream(stream);
 	if (ret < 0)
 		pr_err("Prepare for stream:%s failed: %d", stream->name, ret);
 
-	mutex_unlock(&stream->m_rt->bus->bus_lock);
+	sdw_release_bus_lock(stream);
 	return ret;
 }
 EXPORT_SYMBOL(sdw_prepare_stream);
 
 static int _sdw_enable_stream(struct sdw_stream_runtime *stream)
 {
-	struct sdw_master_runtime *m_rt = stream->m_rt;
-	struct sdw_bus *bus = m_rt->bus;
+	struct sdw_master_runtime *m_rt = NULL;
+	struct sdw_bus *bus = NULL;
 	int ret;
 
-	/* Program params */
-	ret = sdw_program_params(bus);
-	if (ret < 0) {
-		dev_err(bus->dev, "Program params failed: %d", ret);
-		return ret;
-	}
+	/* Enable Master(s) and Slave(s) port(s) associated with stream */
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
 
-	/* Enable port(s) */
-	ret = sdw_enable_disable_ports(m_rt, true);
-	if (ret < 0) {
-		dev_err(bus->dev, "Enable port(s) failed ret: %d", ret);
-		return ret;
+		/* Program params */
+		ret = sdw_program_params(bus);
+		if (ret < 0) {
+			dev_err(bus->dev, "Program params failed: %d", ret);
+			return ret;
+		}
+
+		/* Enable port(s) */
+		ret = sdw_enable_disable_ports(m_rt, true);
+		if (ret < 0) {
+			dev_err(bus->dev, "Enable port(s) failed ret: %d", ret);
+			return ret;
+		}
 	}
 
 	ret = do_bank_switch(stream);
@@ -1413,37 +1471,42 @@ int sdw_enable_stream(struct sdw_stream_runtime *stream)
 		return -EINVAL;
 	}
 
-	mutex_lock(&stream->m_rt->bus->bus_lock);
+	sdw_acquire_bus_lock(stream);
 
 	ret = _sdw_enable_stream(stream);
 	if (ret < 0)
 		pr_err("Enable for stream:%s failed: %d", stream->name, ret);
 
-	mutex_unlock(&stream->m_rt->bus->bus_lock);
+	sdw_release_bus_lock(stream);
 	return ret;
 }
 EXPORT_SYMBOL(sdw_enable_stream);
 
 static int _sdw_disable_stream(struct sdw_stream_runtime *stream)
 {
-	struct sdw_master_runtime *m_rt = stream->m_rt;
-	struct sdw_bus *bus = m_rt->bus;
+	struct sdw_master_runtime *m_rt = NULL;
+	struct sdw_bus *bus = NULL;
 	int ret;
 
-	/* Disable port(s) */
-	ret = sdw_enable_disable_ports(m_rt, false);
-	if (ret < 0) {
-		dev_err(bus->dev, "Disable port(s) failed: %d", ret);
-		return ret;
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		/* Disable port(s) */
+		ret = sdw_enable_disable_ports(m_rt, false);
+		if (ret < 0) {
+			dev_err(bus->dev, "Disable port(s) failed: %d", ret);
+			return ret;
+		}
 	}
-
 	stream->state = SDW_STREAM_DISABLED;
 
-	/* Program params */
-	ret = sdw_program_params(bus);
-	if (ret < 0) {
-		dev_err(bus->dev, "Program params failed: %d", ret);
-		return ret;
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		/* Program params */
+		ret = sdw_program_params(bus);
+		if (ret < 0) {
+			dev_err(bus->dev, "Program params failed: %d", ret);
+			return ret;
+		}
 	}
 
 	return do_bank_switch(stream);
@@ -1465,43 +1528,46 @@ int sdw_disable_stream(struct sdw_stream_runtime *stream)
 		return -EINVAL;
 	}
 
-	mutex_lock(&stream->m_rt->bus->bus_lock);
+	sdw_acquire_bus_lock(stream);
 
 	ret = _sdw_disable_stream(stream);
 	if (ret < 0)
 		pr_err("Disable for stream:%s failed: %d", stream->name, ret);
 
-	mutex_unlock(&stream->m_rt->bus->bus_lock);
+	sdw_release_bus_lock(stream);
 	return ret;
 }
 EXPORT_SYMBOL(sdw_disable_stream);
 
 static int _sdw_deprepare_stream(struct sdw_stream_runtime *stream)
 {
-	struct sdw_master_runtime *m_rt = stream->m_rt;
-	struct sdw_bus *bus = m_rt->bus;
+	struct sdw_master_runtime *m_rt = NULL;
+	struct sdw_bus *bus = NULL;
 	int ret = 0;
 
-	/* De-prepare port(s) */
-	ret = sdw_prep_deprep_ports(m_rt, false);
-	if (ret < 0) {
-		dev_err(bus->dev, "De-prepare port(s) failed: %d", ret);
-		return ret;
-	}
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+		bus = m_rt->bus;
+		/* De-prepare port(s) */
+		ret = sdw_prep_deprep_ports(m_rt, false);
+		if (ret < 0) {
+			dev_err(bus->dev, "De-prepare port(s) failed: %d", ret);
+			return ret;
+		}
 
-	stream->state = SDW_STREAM_DEPREPARED;
+		/* TODO: Update this during Device-Device support */
+		bus->params.bandwidth -= m_rt->stream->params.rate *
+			m_rt->ch_count * m_rt->stream->params.bps;
 
-	/* TODO: Update this during Device-Device support */
-	bus->params.bandwidth -= m_rt->stream->params.rate *
-		m_rt->ch_count * m_rt->stream->params.bps;
+		/* Program params */
+		ret = sdw_program_params(bus);
+		if (ret < 0) {
+			dev_err(bus->dev, "Program params failed: %d", ret);
+			return ret;
+		}
 
-	/* Program params */
-	ret = sdw_program_params(bus);
-	if (ret < 0) {
-		dev_err(bus->dev, "Program params failed: %d", ret);
-		return ret;
 	}
 
+	stream->state = SDW_STREAM_DEPREPARED;
 	return do_bank_switch(stream);
 }
 
@@ -1521,13 +1587,12 @@ int sdw_deprepare_stream(struct sdw_stream_runtime *stream)
 		return -EINVAL;
 	}
 
-	mutex_lock(&stream->m_rt->bus->bus_lock);
-
+	sdw_acquire_bus_lock(stream);
 	ret = _sdw_deprepare_stream(stream);
 	if (ret < 0)
 		pr_err("De-prepare for stream:%d failed: %d", ret, ret);
 
-	mutex_unlock(&stream->m_rt->bus->bus_lock);
+	sdw_release_bus_lock(stream);
 	return ret;
 }
 EXPORT_SYMBOL(sdw_deprepare_stream);
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index ccd8dcdf..03df709 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -768,7 +768,6 @@ struct sdw_stream_params {
  * @params: Stream parameters
  * @state: Current state of the stream
  * @type: Stream type PCM or PDM
- * @m_rt: Master runtime
  * @master_list: List of Master runtime(s) in this stream.
  * master_list can contain only one m_rt per Master instance
  * for a stream
@@ -778,7 +777,6 @@ struct sdw_stream_runtime {
 	struct sdw_stream_params params;
 	enum sdw_stream_state state;
 	enum sdw_stream_type type;
-	struct sdw_master_runtime *m_rt;
 	struct list_head master_list;
 };
 
-- 
2.7.4

[PATCH v7 08/10] soundwire: keep track of Masters in a stream

[Shreyas NC]

A multi link bankswitch can be done if the hardware supports and
the stream is handled by multiple Master(s).

This preparatory patch adds support to track m_rt in a stream.
Modifying m_rt_count and usage is added as part of the next patch.

Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
---
 drivers/soundwire/stream.c    | 1 +
 include/linux/soundwire/sdw.h | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
index 0d04d84..088b939 100644
--- a/drivers/soundwire/stream.c
+++ b/drivers/soundwire/stream.c
@@ -759,6 +759,7 @@ struct sdw_stream_runtime *sdw_alloc_stream(char *stream_name)
 	stream->name = stream_name;
 	INIT_LIST_HEAD(&stream->master_list);
 	stream->state = SDW_STREAM_ALLOCATED;
+	stream->m_rt_count = 0;
 
 	return stream;
 }
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 03df709..214e146 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -771,6 +771,7 @@ struct sdw_stream_params {
  * @master_list: List of Master runtime(s) in this stream.
  * master_list can contain only one m_rt per Master instance
  * for a stream
+ * @m_rt_count: Count of Master runtime(s) in this stream
  */
 struct sdw_stream_runtime {
 	char *name;
@@ -778,6 +779,7 @@ struct sdw_stream_runtime {
 	enum sdw_stream_state state;
 	enum sdw_stream_type type;
 	struct list_head master_list;
+	int m_rt_count;
 };
 
 struct sdw_stream_runtime *sdw_alloc_stream(char *stream_name);
-- 
2.7.4

[PATCH v7 09/10] soundwire: Add support for multi link bank switch

[Shreyas NC]

In cases of multiple Masters in a stream, synchronization
between multiple Master(s) is achieved by performing bank switch
together and using Master methods.

Add sdw_ml_bank_switch() to wait for completion of bank switch.

Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
---
 drivers/soundwire/bus.c       |   5 ++
 drivers/soundwire/bus.h       |   2 +
 drivers/soundwire/stream.c    | 145 ++++++++++++++++++++++++++++++++++++++----
 include/linux/soundwire/sdw.h |   4 ++
 4 files changed, 144 insertions(+), 12 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index dbabd5e..1cbfedf 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -35,6 +35,11 @@ int sdw_add_bus_master(struct sdw_bus *bus)
 	INIT_LIST_HEAD(&bus->slaves);
 	INIT_LIST_HEAD(&bus->m_rt_list);
 
+	/*
+	 * Initialize multi_link flag
+	 * TODO: populate this flag by reading property from FW node
+	 */
+	bus->multi_link = false;
 	if (bus->ops->read_prop) {
 		ret = bus->ops->read_prop(bus);
 		if (ret < 0) {
diff --git a/drivers/soundwire/bus.h b/drivers/soundwire/bus.h
index b6cfbdf..c77de05 100644
--- a/drivers/soundwire/bus.h
+++ b/drivers/soundwire/bus.h
@@ -4,6 +4,8 @@
 #ifndef __SDW_BUS_H
 #define __SDW_BUS_H
 
+#define DEFAULT_BANK_SWITCH_TIMEOUT 3000
+
 #if IS_ENABLED(CONFIG_ACPI)
 int sdw_acpi_find_slaves(struct sdw_bus *bus);
 #else
diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
index 088b939..515b2f6 100644
--- a/drivers/soundwire/stream.c
+++ b/drivers/soundwire/stream.c
@@ -626,9 +626,10 @@ static int sdw_program_params(struct sdw_bus *bus)
 	return ret;
 }
 
-static int sdw_bank_switch(struct sdw_bus *bus)
+static int sdw_bank_switch(struct sdw_bus *bus, int m_rt_count)
 {
 	int col_index, row_index;
+	bool multi_link;
 	struct sdw_msg *wr_msg;
 	u8 *wbuf = NULL;
 	int ret = 0;
@@ -638,6 +639,8 @@ static int sdw_bank_switch(struct sdw_bus *bus)
 	if (!wr_msg)
 		return -ENOMEM;
 
+	bus->defer_msg.msg = wr_msg;
+
 	wbuf = kzalloc(sizeof(*wbuf), GFP_KERNEL);
 	if (!wbuf) {
 		ret = -ENOMEM;
@@ -658,17 +661,29 @@ static int sdw_bank_switch(struct sdw_bus *bus)
 					SDW_MSG_FLAG_WRITE, wbuf);
 	wr_msg->ssp_sync = true;
 
-	ret = sdw_transfer(bus, wr_msg);
+	/*
+	 * Set the multi_link flag only when both the hardware supports
+	 * and there is a stream handled by multiple masters
+	 */
+	multi_link = bus->multi_link && (m_rt_count > 1);
+
+	if (multi_link)
+		ret = sdw_transfer_defer(bus, wr_msg, &bus->defer_msg);
+	else
+		ret = sdw_transfer(bus, wr_msg);
+
 	if (ret < 0) {
 		dev_err(bus->dev, "Slave frame_ctrl reg write failed");
 		goto error;
 	}
 
-	kfree(wr_msg);
-	kfree(wbuf);
-	bus->defer_msg.msg = NULL;
-	bus->params.curr_bank = !bus->params.curr_bank;
-	bus->params.next_bank = !bus->params.next_bank;
+	if (!bus->multi_link) {
+		kfree(wr_msg);
+		kfree(wbuf);
+		bus->defer_msg.msg = NULL;
+		bus->params.curr_bank = !bus->params.curr_bank;
+		bus->params.next_bank = !bus->params.next_bank;
+	}
 
 	return 0;
 
@@ -679,36 +694,87 @@ static int sdw_bank_switch(struct sdw_bus *bus)
 	return ret;
 }
 
+/**
+ * sdw_ml_sync_bank_switch: Multilink register bank switch
+ *
+ * @bus: SDW bus instance
+ *
+ * Caller function should free the buffers on error
+ */
+static int sdw_ml_sync_bank_switch(struct sdw_bus *bus)
+{
+	unsigned long time_left;
+
+	if (!bus->multi_link)
+		return 0;
+
+	/* Wait for completion of transfer */
+	time_left = wait_for_completion_timeout(&bus->defer_msg.complete,
+						bus->bank_switch_timeout);
+
+	if (!time_left) {
+		dev_err(bus->dev, "Controller Timed out on bank switch");
+		return -ETIMEDOUT;
+	}
+
+	bus->params.curr_bank = !bus->params.curr_bank;
+	bus->params.next_bank = !bus->params.next_bank;
+
+	if (bus->defer_msg.msg) {
+		kfree(bus->defer_msg.msg->buf);
+		kfree(bus->defer_msg.msg);
+	}
+
+	return 0;
+}
+
 static int do_bank_switch(struct sdw_stream_runtime *stream)
 {
 	struct sdw_master_runtime *m_rt = NULL;
 	const struct sdw_master_ops *ops;
 	struct sdw_bus *bus = NULL;
+	bool multi_link = false;
 	int ret = 0;
 
-
 	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
 		bus = m_rt->bus;
 		ops = bus->ops;
 
+		if (bus->multi_link) {
+			multi_link = true;
+			mutex_lock(&bus->msg_lock);
+		}
+
 		/* Pre-bank switch */
 		if (ops->pre_bank_switch) {
 			ret = ops->pre_bank_switch(bus);
 			if (ret < 0) {
 				dev_err(bus->dev,
 					"Pre bank switch op failed: %d", ret);
-				return ret;
+				goto msg_unlock;
 			}
 		}
 
-		/* Bank switch */
-		ret = sdw_bank_switch(bus);
+		/*
+		 * Perform Bank switch operation.
+		 * For multi link cases, the actual bank switch is
+		 * synchronized across all Masters and happens later as a
+		 * part of post_bank_switch ops.
+		 */
+		ret = sdw_bank_switch(bus, stream->m_rt_count);
 		if (ret < 0) {
 			dev_err(bus->dev, "Bank switch failed: %d", ret);
-			return ret;
+			goto error;
+
 		}
 	}
 
+	/*
+	 * For multi link cases, it is expected that the bank switch is
+	 * triggered by the post_bank_switch for the first Master in the list
+	 * and for the other Masters the post_bank_switch() should return doing
+	 * nothing.
+	 */
 	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
 		bus = m_rt->bus;
 		ops = bus->ops;
@@ -719,7 +785,47 @@ static int do_bank_switch(struct sdw_stream_runtime *stream)
 			if (ret < 0) {
 				dev_err(bus->dev,
 					"Post bank switch op failed: %d", ret);
+				goto error;
 			}
+		} else if (bus->multi_link && stream->m_rt_count > 1) {
+			dev_err(bus->dev,
+				"Post bank switch ops not implemented");
+			goto error;
+		}
+
+		/* Set the bank switch timeout to default, if not set */
+		if (!bus->bank_switch_timeout)
+			bus->bank_switch_timeout = DEFAULT_BANK_SWITCH_TIMEOUT;
+
+		/* Check if bank switch was successful */
+		ret = sdw_ml_sync_bank_switch(bus);
+		if (ret < 0) {
+			dev_err(bus->dev,
+				"multi link bank switch failed: %d", ret);
+			goto error;
+		}
+
+		mutex_unlock(&bus->msg_lock);
+	}
+
+	return ret;
+
+error:
+	list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+
+		bus = m_rt->bus;
+
+		kfree(bus->defer_msg.msg->buf);
+		kfree(bus->defer_msg.msg);
+	}
+
+msg_unlock:
+
+	if (multi_link) {
+		list_for_each_entry(m_rt, &stream->master_list, stream_node) {
+			bus = m_rt->bus;
+			if (mutex_is_locked(&bus->msg_lock))
+				mutex_unlock(&bus->msg_lock);
 		}
 	}
 
@@ -965,6 +1071,7 @@ int sdw_stream_remove_master(struct sdw_bus *bus,
 
 		sdw_master_port_release(bus, m_rt);
 		sdw_release_master_stream(m_rt, stream);
+		stream->m_rt_count--;
 	}
 
 	if (list_empty(&stream->master_list))
@@ -1151,6 +1258,18 @@ int sdw_stream_add_master(struct sdw_bus *bus,
 
 	mutex_lock(&bus->bus_lock);
 
+	/*
+	 * For multi link streams, add the second master only if
+	 * the bus supports it.
+	 * Check if bus->multi_link is set
+	 */
+	if (!bus->multi_link && stream->m_rt_count > 0) {
+		dev_err(bus->dev,
+			"Multilink not supported, link %d", bus->link_id);
+		ret = -EINVAL;
+		goto unlock;
+	}
+
 	m_rt = sdw_alloc_master_rt(bus, stream_config, stream);
 	if (!m_rt) {
 		dev_err(bus->dev,
@@ -1168,6 +1287,8 @@ int sdw_stream_add_master(struct sdw_bus *bus,
 	if (ret)
 		goto stream_error;
 
+	stream->m_rt_count++;
+
 	goto unlock;
 
 stream_error:
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 214e146..df31391 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -678,6 +678,9 @@ struct sdw_master_ops {
  * @defer_msg: Defer message
  * @clk_stop_timeout: Clock stop timeout computed
  * @bank_switch_timeout: Bank switch timeout computed
+ * @multi_link: Store bus property that indicates if multi links
+ * are supported. This flag is populated by drivers after reading
+ * appropriate firmware (ACPI/DT).
  */
 struct sdw_bus {
 	struct device *dev;
@@ -694,6 +697,7 @@ struct sdw_bus {
 	struct sdw_defer defer_msg;
 	unsigned int clk_stop_timeout;
 	u32 bank_switch_timeout;
+	bool multi_link;
 };
 
 int sdw_add_bus_master(struct sdw_bus *bus);
-- 
2.7.4

Re: [PATCH v7 09/10] soundwire: Add support for multi link bank switch

[Pierre-Louis Bossart]

The series looks pretty good now, I just found one possible improvement 
below
Thanks!

>   
> -static int sdw_bank_switch(struct sdw_bus *bus)
> +static int sdw_bank_switch(struct sdw_bus *bus, int m_rt_count)
>   {
>   	int col_index, row_index;
> +	bool multi_link;
>   	struct sdw_msg *wr_msg;
>   	u8 *wbuf = NULL;
>   	int ret = 0;
> @@ -638,6 +639,8 @@ static int sdw_bank_switch(struct sdw_bus *bus)
>   	if (!wr_msg)
>   		return -ENOMEM;
>   
> +	bus->defer_msg.msg = wr_msg;
> +
>   	wbuf = kzalloc(sizeof(*wbuf), GFP_KERNEL);
>   	if (!wbuf) {
>   		ret = -ENOMEM;
> @@ -658,17 +661,29 @@ static int sdw_bank_switch(struct sdw_bus *bus)
>   					SDW_MSG_FLAG_WRITE, wbuf);
>   	wr_msg->ssp_sync = true;
>   
> -	ret = sdw_transfer(bus, wr_msg);
> +	/*
> +	 * Set the multi_link flag only when both the hardware supports
> +	 * and there is a stream handled by multiple masters
> +	 */
> +	multi_link = bus->multi_link && (m_rt_count > 1);
> +
> +	if (multi_link)
> +		ret = sdw_transfer_defer(bus, wr_msg, &bus->defer_msg);
> +	else
> +		ret = sdw_transfer(bus, wr_msg);
> +
>   	if (ret < 0) {
>   		dev_err(bus->dev, "Slave frame_ctrl reg write failed");
>   		goto error;
>   	}
>   
> -	kfree(wr_msg);
> -	kfree(wbuf);
> -	bus->defer_msg.msg = NULL;
> -	bus->params.curr_bank = !bus->params.curr_bank;
> -	bus->params.next_bank = !bus->params.next_bank;
> +	if (!bus->multi_link) {
> +		kfree(wr_msg);
> +		kfree(wbuf);
> +		bus->defer_msg.msg = NULL;
> +		bus->params.curr_bank = !bus->params.curr_bank;
> +		bus->params.next_bank = !bus->params.next_bank;
> +	}

Should this test be extended to the case where the bus can support 
multi-link but m_rt_count ==1
should it be
if (!multi_link)
?

Re: [PATCH v7 09/10] soundwire: Add support for multi link bank switch

[Shreyas Nc]

> >+		ret = sdw_transfer_defer(bus, wr_msg, &bus->defer_msg);
> >+	else
> >+		ret = sdw_transfer(bus, wr_msg);
> >+
> >  	if (ret < 0) {
> >  		dev_err(bus->dev, "Slave frame_ctrl reg write failed");
> >  		goto error;
> >  	}
> >-	kfree(wr_msg);
> >-	kfree(wbuf);
> >-	bus->defer_msg.msg = NULL;
> >-	bus->params.curr_bank = !bus->params.curr_bank;
> >-	bus->params.next_bank = !bus->params.next_bank;
> >+	if (!bus->multi_link) {
> >+		kfree(wr_msg);
> >+		kfree(wbuf);
> >+		bus->defer_msg.msg = NULL;
> >+		bus->params.curr_bank = !bus->params.curr_bank;
> >+		bus->params.next_bank = !bus->params.next_bank;
> >+	}
> 
> Should this test be extended to the case where the bus can support
> multi-link but m_rt_count ==1
> should it be
> if (!multi_link)
> ?
>
Sure, makes sense to add the right check.
v8 on its way ..

--Shreyas

-- 

[PATCH v7 10/10] soundwire: intel: Add pre/post bank switch ops

[Shreyas NC]

To support multi link on Intel platforms, we need to update
SDW SHIM registers.

So, add pre/post bank switch ops for the same in Intel driver.

Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
---
 drivers/soundwire/intel.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index 0a8990e..da7f91f 100644
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -398,6 +398,69 @@ static int intel_config_stream(struct sdw_intel *sdw,
 }
 
 /*
+ * bank switch routines
+ */
+
+static int intel_pre_bank_switch(struct sdw_bus *bus)
+{
+	struct sdw_cdns *cdns = bus_to_cdns(bus);
+	struct sdw_intel *sdw = cdns_to_intel(cdns);
+	void __iomem *shim = sdw->res->shim;
+	int sync_reg;
+
+	/* Write to register only for multi-link */
+	if (!bus->multi_link)
+		return 0;
+
+	/* Read SYNC register */
+	sync_reg = intel_readl(shim, SDW_SHIM_SYNC);
+	sync_reg |= SDW_SHIM_SYNC_CMDSYNC << sdw->instance;
+	intel_writel(shim, SDW_SHIM_SYNC, sync_reg);
+
+	return 0;
+}
+
+static int intel_post_bank_switch(struct sdw_bus *bus)
+{
+	struct sdw_cdns *cdns = bus_to_cdns(bus);
+	struct sdw_intel *sdw = cdns_to_intel(cdns);
+	void __iomem *shim = sdw->res->shim;
+	int sync_reg, ret;
+
+	/* Write to register only for multi-link */
+	if (!bus->multi_link)
+		return 0;
+
+	/* Read SYNC register */
+	sync_reg = intel_readl(shim, SDW_SHIM_SYNC);
+
+	/*
+	 * post_bank_switch() ops is called from the bus in loop for
+	 * all the Masters in the steam with the expectation that
+	 * we trigger the bankswitch for the only first Master in the list
+	 * and do nothing for the other Masters
+	 *
+	 * So, set the SYNCGO bit only if CMDSYNC bit is set for any Master.
+	 */
+	if (!(sync_reg & SDW_SHIM_SYNC_CMDSYNC_MASK))
+		return 0;
+
+	/*
+	 * Set SyncGO bit to synchronously trigger a bank switch for
+	 * all the masters. A write to SYNCGO bit clears CMDSYNC bit for all
+	 * the Masters.
+	 */
+	sync_reg |= SDW_SHIM_SYNC_SYNCGO;
+
+	ret = intel_clear_bit(shim, SDW_SHIM_SYNC, sync_reg,
+					SDW_SHIM_SYNC_SYNCGO);
+	if (ret < 0)
+		dev_err(sdw->cdns.dev, "Post bank switch failed: %d", ret);
+
+	return ret;
+}
+
+/*
  * DAI routines
  */
 
@@ -750,6 +813,8 @@ static struct sdw_master_ops sdw_intel_ops = {
 	.xfer_msg_defer = cdns_xfer_msg_defer,
 	.reset_page_addr = cdns_reset_page_addr,
 	.set_bus_conf = cdns_bus_conf,
+	.pre_bank_switch = intel_pre_bank_switch,
+	.post_bank_switch = intel_post_bank_switch,
 };
 
 /*
-- 
2.7.4