[PATCH 1/4] Documentation: SoundWire: clarify TDM mode support

[PATCH 1/4] Documentation: SoundWire: clarify TDM mode support

[Bard Liao]

From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

The current description of stream topologies does not explicitly
mention 'mirror' topologies used for audio amplifiers, where all
amplifiers see the same data and generate a different output based on
configuration or dynamic information. Add examples and notes to
explain how channels can be transmitted and mapped.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
---
 Documentation/driver-api/soundwire/stream.rst | 89 ++++++++++++++++++-
 1 file changed, 86 insertions(+), 3 deletions(-)

diff --git a/Documentation/driver-api/soundwire/stream.rst b/Documentation/driver-api/soundwire/stream.rst
index 8bceece51554..1b386076402c 100644
--- a/Documentation/driver-api/soundwire/stream.rst
+++ b/Documentation/driver-api/soundwire/stream.rst
@@ -75,8 +75,33 @@ Slaves are using single port. ::
 	                                                   |     (Data)    |
 	                                                   +---------------+
 
+Example 4: Stereo Stream with L and R channels is rendered by
+Master. Both of the L and R channels are received by two different
+Slaves. Master and both Slaves are using single port handling
+L+R. Each Slave device processes the L + R data locally, typically
+based on static configuration or dynamic orientation, and may drive
+one or more speakers. ::
 
-Example 4: Stereo Stream with L and R channel is rendered by two different
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +---------+------------------------+     Slave     |
+	|   Interface   |         |                        |   Interface   |
+	|               |         |                        |       1       |
+	|               |         |           Data Signal  |               |
+	|    L  +  R    +---+------------------------------+     L + R     |
+	|     (Data)    |   |     |    Data Direction      |     (Data)    |
+	+---------------+   |     |   +------------->      +---------------+
+	                    |     |
+	                    |     |
+	                    |     |                        +---------------+
+	                    |     +----------------------> |     Slave     |
+	                    |                              |   Interface   |
+	                    |                              |       2       |
+	                    |                              |               |
+	                    +----------------------------> |     L + R     |
+	                                                   |     (Data)    |
+	                                                   +---------------+
+
+Example 5: Stereo Stream with L and R channel is rendered by two different
 Ports of the Master and is received by only single Port of the Slave
 interface. ::
 
@@ -101,7 +126,7 @@ interface. ::
 	+--------------------+                             |                |
 							   +----------------+
 
-Example 5: Stereo Stream with L and R channel is rendered by 2 Masters, each
+Example 6: 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. ::
 
@@ -123,12 +148,70 @@ receiving one channel. Both Masters and both Slaves are using single port. ::
 	|     (Data)    |     Data Direction               |     (Data)    |
 	+---------------+  +----------------------->       +---------------+
 
-Note: In multi-link cases like above, to lock, one would acquire a global
+Example 7: Stereo Stream with L and R channel is rendered by 2
+Masters, each rendering both channels. Each Slave receives L + R. This
+is the same application as Example 4 but with Slaves placed on
+separate links. ::
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       1       |                                  |       1       |
+	|               |                     Data Signal  |               |
+	|     L + R     +----------------------------------+     L + R     |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       2       |                                  |       2       |
+	|               |                     Data Signal  |               |
+	|     L + R     +----------------------------------+     L + R     |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+Example 8: 4-channel Stream is rendered by 2 Masters, each rendering a
+2 channels. Each Slave receives 2 channels. ::
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       1       |                                  |       1       |
+	|               |                     Data Signal  |               |
+	|    L1 + R1    +----------------------------------+    L1 + R1    |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       2       |                                  |       2       |
+	|               |                     Data Signal  |               |
+	|     L2 + R2   +----------------------------------+    L2 + R2    |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+Note1: 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.
 
+Note2: A Slave device may be configured to receive all channels
+transmitted on a link for a given Stream (Example 4) or just a subset
+of the data (Example 3). The configuration of the Slave device is not
+handled by a SoundWire subsystem API, but instead by the
+snd_soc_dai_set_tdm_slot() API. The platform or machine driver will
+typically configure which of the slots are used. For Example 4, the
+same slots would be used by all Devices, while for Example 3 the Slave
+Device1 would use e.g. Slot 0 and Slave device2 slot 1.
+
+Note3: Multiple Sink ports can extract the same information for the
+same bitSlots in the SoundWire frame, however multiple Source ports
+shall be configured with different bitSlot configurations. This is the
+same limitation as with I2S/PCM TDM usages.
+
 SoundWire Stream Management flow
 ================================
 
-- 
2.17.1

[PATCH 2/4] soundwire: slave: don't init debugfs on device registration error

[Bard Liao]

From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

The error handling flow seems incorrect, there is no reason to try and
add debugfs support if the device registration did not
succeed. Return on error.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
---
 drivers/soundwire/slave.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/soundwire/slave.c b/drivers/soundwire/slave.c
index aace57fae7f8..4bacdb187eab 100644
--- a/drivers/soundwire/slave.c
+++ b/drivers/soundwire/slave.c
@@ -68,6 +68,8 @@ static int sdw_slave_add(struct sdw_bus *bus,
 		list_del(&slave->node);
 		mutex_unlock(&bus->bus_lock);
 		put_device(&slave->dev);
+
+		return ret;
 	}
 	sdw_slave_debugfs_init(slave);
 
-- 
2.17.1

[PATCH 3/4] soundwire: debugfs: clarify SDPX license with GPL-2.0-only

[Bard Liao]

From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

Follow recommendation to use GPL-2.0-only

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
---
 drivers/soundwire/debugfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/soundwire/debugfs.c b/drivers/soundwire/debugfs.c
index fb1140e82b86..b6cad0d59b7b 100644
--- a/drivers/soundwire/debugfs.c
+++ b/drivers/soundwire/debugfs.c
@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 // Copyright(c) 2017-2019 Intel Corporation.
 
 #include <linux/device.h>
-- 
2.17.1

[PATCH 4/4] soundwire: bus: reduce verbosity on enumeration

[Bard Liao]

From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

No need to repeat the same info log on all enumerations (essentially
each power-up), keep it as debug information.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
---
 drivers/soundwire/bus.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 488c3c9e4947..f9a078ce76bc 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -563,9 +563,9 @@ static int sdw_assign_device_num(struct sdw_slave *slave)
 	}
 
 	if (!new_device)
-		dev_info(slave->bus->dev,
-			 "Slave already registered, reusing dev_num:%d\n",
-			 slave->dev_num);
+		dev_dbg(slave->bus->dev,
+			"Slave already registered, reusing dev_num:%d\n",
+			slave->dev_num);
 
 	/* Clear the slave->dev_num to transfer message on device 0 */
 	dev_num = slave->dev_num;
-- 
2.17.1

Re: [PATCH 1/4] Documentation: SoundWire: clarify TDM mode support

[Vinod Koul]

On 20-04-20, 02:51, Bard Liao wrote:
> From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
> 
> The current description of stream topologies does not explicitly
> mention 'mirror' topologies used for audio amplifiers, where all
> amplifiers see the same data and generate a different output based on
> configuration or dynamic information. Add examples and notes to
> explain how channels can be transmitted and mapped.

Applied all, thanks
-- 
~Vinod