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Message-Id: <20200419185117.4233-1-yung-chuan.liao@linux.intel.com>
Date: Mon, 20 Apr 2020 02:51:14 +0800
From: Bard Liao <yung-chuan.liao@...ux.intel.com>
To: alsa-devel@...a-project.org, vkoul@...nel.org
Cc: linux-kernel@...r.kernel.org, tiwai@...e.de, broonie@...nel.org,
gregkh@...uxfoundation.org, jank@...ence.com,
srinivas.kandagatla@...aro.org, rander.wang@...ux.intel.com,
ranjani.sridharan@...ux.intel.com, hui.wang@...onical.com,
pierre-louis.bossart@...ux.intel.com, sanyog.r.kale@...el.com,
slawomir.blauciak@...el.com, mengdong.lin@...el.com,
bard.liao@...el.com
Subject: [PATCH 1/4] Documentation: SoundWire: clarify TDM mode support
From: Pierre-Louis Bossart <pierre-louis.bossart@...ux.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@...ux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@...ux.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
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