[PATCH BlueZ v2 2/9] doc/btmon: Split LE Audio Protocol Flow into btmon-le-audio.rst

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

Move the LE AUDIO PROTOCOL FLOW section (including CIS unicast,
BIS broadcast, and BIG sync flows) into a standalone file and
replace it with an RST include directive. This is the largest
split section (660 lines) and was being truncated away in
context-limited analysis.
---
 doc/btmon-le-audio.rst | 655 ++++++++++++++++++++++++++++++++++++++++
 doc/btmon.rst          | 656 +----------------------------------------
 2 files changed, 657 insertions(+), 654 deletions(-)
 create mode 100644 doc/btmon-le-audio.rst

diff --git a/doc/btmon-le-audio.rst b/doc/btmon-le-audio.rst
new file mode 100644
index 000000000000..db909ac38e47
--- /dev/null
+++ b/doc/btmon-le-audio.rst
@@ -0,0 +1,655 @@
+.. This file is included by btmon.rst.
+
+LE AUDIO PROTOCOL FLOW
+=======================
+
+LE Audio uses a multi-layer protocol stack visible in btmon traces.
+The setup sequence involves ATT operations on specific GATT
+characteristics (PACS, ASCS) followed by HCI-level CIS/BIG
+management. btmon fully decodes all layers.
+
+PACS: Published Audio Capabilities
+------------------------------------
+
+Before audio streaming begins, devices exchange codec capabilities
+via the Published Audio Capabilities Service (PACS). The client reads
+PACS characteristics to learn what the remote device supports.
+
+**Sink PAC read** (remote device's receive capabilities)::
+
+    < ACL Data TX: Handle 2048 flags 0x00 dlen 7    #550 [hci0] 0.824003
+          ATT: Read Request (0x0a) len 2
+            Handle: 0x0075
+
+    > ACL Data RX: Handle 2048 flags 0x02 dlen 30   #552 [hci0] 0.886556
+          ATT: Read Response (0x0b) len 25
+            Handle: 0x0075
+              Number of PAC(s): 1
+              Codec: LC3 (0x06)
+              Codec Specific Capabilities: #0
+                Sampling Frequency: 8000 Hz 16000 Hz 24000 Hz 32000 Hz 48000 Hz
+                Frame Duration: 7.5 ms 10 ms
+                Audio Channel Counts: 1
+                Frame Length: 26 - 240
+
+The PAC record shows codec capabilities using LTV (Length-Type-Value)
+encoding. Key fields:
+
+- **Codec** -- ``LC3 (0x06)`` is the mandatory LE Audio codec
+- **Sampling Frequency** -- Supported sample rates (bitmask)
+- **Frame Duration** -- Supported frame durations (7.5 ms and/or 10 ms)
+- **Audio Channel Counts** -- Supported channel counts
+- **Frame Length** -- Min and max octets per codec frame
+
+**Audio Locations** (channel assignment)::
+
+    > ACL Data RX: Handle 2048 flags 0x02 dlen 9    #554 [hci0] 0.948003
+          ATT: Read Response (0x0b) len 4
+            Handle: 0x0077
+              Location: Front Left
+
+**Available Audio Contexts** (current use cases)::
+
+    > ACL Data RX: Handle 2048 flags 0x02 dlen 9    #558 [hci0] 1.012556
+          ATT: Read Response (0x0b) len 4
+            Handle: 0x007b
+              Sink Context: Media Conversational
+              Source Context: Unspecified
+
+ASCS: Audio Stream Control
+----------------------------
+
+The Audio Stream Control Service (ASCS) manages the ASE (Audio Stream
+Endpoint) state machine. Each ASE transitions through a defined set
+of states as streaming is set up and torn down.
+
+**ASE State Machine**::
+
+    Idle ──► Codec Configured ──► QoS Configured ──► Enabling ──► Streaming
+                                                                      │
+    Idle ◄── Releasing ◄──────── Disabling ◄─────────────────────────┘
+
+**ASE Status notification** (state change)::
+
+    > ACL Data RX: Handle 2048 flags 0x02 dlen 20   #580 [hci0] 1.456003
+          ATT: Handle Value Notification (0x1b) len 15
+            Handle: 0x0088
+              ASE ID: 0x01
+              State: Codec Configured (0x01)
+                Framing: Unframed PDUs supported (0x00)
+                PHY: 0x02
+                  LE 2M PHY (0x02)
+                RTN: 2
+                Max Transport Latency: 10
+                Presentation Delay Min: 20000 us
+                Presentation Delay Max: 40000 us
+                Preferred Presentation Delay Min: 20000 us
+                Preferred Presentation Delay Max: 40000 us
+                Codec: LC3 (0x06)
+                  Sampling Frequency: 48000 Hz
+                  Frame Duration: 10 ms
+                  Audio Channel Allocation: Front Left
+                  Frame Length: 120
+
+**ASE Control Point operations** drive state transitions. The client
+writes to the ASE Control Point characteristic to issue commands::
+
+    < ACL Data TX: Handle 2048 flags 0x00 dlen 25   #582 [hci0] 1.518003
+          ATT: Write Request (0x12) len 20
+            Handle: 0x008b
+              ASE Control Point: Config Codec (0x01)
+                ASE ID: 0x01
+                Target Latency: Low Latency (0x01)
+                PHY: LE 2M PHY
+                Codec: LC3 (0x06)
+                  Sampling Frequency: 48000 Hz
+                  Frame Duration: 10 ms
+                  Audio Channel Allocation: Front Left
+                  Frame Length: 120
+
+ASE Control Point commands:
+
+.. list-table::
+   :header-rows: 1
+   :widths: 10 25 65
+
+   * - Opcode
+     - Command
+     - Purpose
+   * - 0x01
+     - Config Codec
+     - Select codec and parameters (Idle → Codec Configured)
+   * - 0x02
+     - Config QoS
+     - Set CIG/CIS IDs and QoS params (Codec Configured → QoS Configured)
+   * - 0x03
+     - Enable
+     - Start ASE with metadata (QoS Configured → Enabling)
+   * - 0x04
+     - Receiver Start Ready
+     - Signal receiver readiness (Enabling → Streaming, server-side)
+   * - 0x05
+     - Disable
+     - Stop streaming (Streaming → Disabling)
+   * - 0x06
+     - Receiver Stop Ready
+     - Signal receiver stopped
+   * - 0x07
+     - Update Metadata
+     - Change metadata during streaming
+   * - 0x08
+     - Release
+     - Tear down ASE (any → Releasing → Idle)
+
+CIS Setup and Teardown
+------------------------
+
+After ASE QoS Configuration, the host creates Connected Isochronous
+Streams (CIS) at the HCI level.
+
+**CIG Parameters** (configure the CIS group)::
+
+    < HCI Command: LE Set CIG Parameters (0x08|0x0062) plen 26  #590 [hci0] 1.624003
+          CIG ID: 0x00
+          Central to Peripheral SDU Interval: 10000 us
+          Peripheral to Central SDU Interval: 10000 us
+          SCA: 0x00
+          Packing: Sequential (0x00)
+          Framing: Unframed (0x00)
+          Central to Peripheral Max Latency: 10 ms
+          Peripheral to Central Max Latency: 10 ms
+          Number of CIS: 1
+          CIS ID: 0x00
+          Central to Peripheral Max SDU: 120
+          Peripheral to Central Max SDU: 0
+          Central to Peripheral PHY: LE 2M PHY
+          Peripheral to Central PHY: LE 2M PHY
+          Central to Peripheral RTN: 2
+          Peripheral to Central RTN: 2
+
+    > HCI Event: Command Complete (0x0e) plen 8              #592 [hci0] 1.624556
+          LE Set CIG Parameters (0x08|0x0062) ncmd 1
+            Status: Success (0x00)
+            CIG ID: 0x00
+            Number of Handles: 1
+            Connection Handle: 2064
+
+**CIS Creation**::
+
+    < HCI Command: LE Create CIS (0x08|0x0064) plen 9       #594 [hci0] 1.688003
+          Number of CIS: 1
+          CIS Handle: 2064
+          ACL Handle: 2048
+
+    > HCI Event: LE Meta Event (0x3e) plen 29                #596 [hci0] 1.756556
+          LE CIS Established (0x19)
+            Status: Success (0x00)
+            Connection Handle: 2064
+            CIG Sync Delay: 5000 us
+            CIS Sync Delay: 5000 us
+            Central to Peripheral Latency: 10000 us
+            Peripheral to Central Latency: 10000 us
+            Central to Peripheral PHY: LE 2M PHY
+            Peripheral to Central PHY: LE 2M PHY
+            NSE: 3
+            Central to Peripheral BN: 1
+            Peripheral to Central BN: 0
+            Central to Peripheral FT: 2
+            Peripheral to Central FT: 2
+            Max PDU C to P: 120
+            Max PDU P to C: 0
+            ISO Interval: 10.00 msec (0x0008)
+
+Note that the CIS Handle (2064) is different from the ACL Handle
+(2048). CIS data packets use the CIS handle.
+
+**ISO Data Path Setup**::
+
+    < HCI Command: LE Setup ISO Data Path (0x08|0x006e) plen 13  #598 [hci0] 1.820003
+          Handle: 2064
+          Data Path Direction: Input (Host to Controller) (0x00)
+          Data Path ID: HCI (0x00)
+          Coding Format: LC3 (0x06)
+          Company ID: 0x0000
+          Vendor Codec ID: 0x0000
+          Controller Delay: 0 us
+
+After this, ISO data packets flow on the CIS handle::
+
+    < ISO Data TS: Handle 2064 flags 0x02 dlen 124  #600 [hci0] 1.884003
+
+Broadcast Audio (BIG)
+----------------------
+
+Broadcast Isochronous Streams use BIG (Broadcast Isochronous Group)
+instead of CIS. The setup involves periodic advertising with BASE
+(Broadcast Audio Source Endpoint) announcements.
+
+**BASE announcement** (in periodic advertising data)::
+
+    > HCI Event: LE Meta Event (0x3e) plen 80                #200 [hci0] 0.500003
+          LE Periodic Advertising Report (0x0f)
+            ...
+            Service Data: Basic Audio Announcement (0x1851)
+              Presentation Delay: 40000 us
+              Number of Subgroups: 1
+                Number of BIS: 2
+                Codec: LC3 (0x06)
+                  Sampling Frequency: 48000 Hz
+                  Frame Duration: 10 ms
+                  Frame Length: 120
+                BIS #1
+                  Audio Channel Allocation: Front Left
+                BIS #2
+                  Audio Channel Allocation: Front Right
+
+**BIG creation** (source side)::
+
+    < HCI Command: LE Create BIG (0x08|0x0068) plen 31      #210 [hci0] 0.600003
+          BIG Handle: 0x00
+          Advertising Handle: 0x01
+          Number of BIS: 2
+          SDU Interval: 10000 us
+          Max SDU: 120
+          Max Latency: 10 ms
+          RTN: 2
+          PHY: LE 2M PHY
+          Packing: Sequential (0x00)
+          Framing: Unframed (0x00)
+          Encryption: Unencrypted (0x00)
+
+**BIG sync** (receiver side)::
+
+    < HCI Command: LE BIG Create Sync (0x08|0x006b) plen 15  #220 [hci0] 0.700003
+          BIG Handle: 0x00
+          Sync Handle: 0x0001
+          Encryption: Unencrypted (0x00)
+          Number of BIS: 2
+          BIS: 0x01
+          BIS: 0x02
+
+BIG Sync Receiver Flow
+~~~~~~~~~~~~~~~~~~~~~~
+
+A receiver must complete a specific sequence of steps before it can
+receive broadcast audio. The critical prerequisite chain is:
+
+1. **Synchronize to periodic advertising** -- the receiver must first
+   discover and sync to the broadcaster's periodic advertising train.
+2. **Receive PA Reports with BASE** -- the periodic advertising data
+   contains the BASE (Broadcast Audio Source Endpoint) structure
+   describing the broadcast's codec configuration.
+3. **Receive BIG Info Advertising Report** -- this event tells the
+   receiver that a BIG exists on the periodic advertising train and
+   provides its parameters (number of BIS, encryption, SDU interval,
+   etc.). **This is the critical gate**: without receiving BIG Info,
+   the receiver cannot issue ``LE BIG Create Sync``.
+4. **Issue LE BIG Create Sync** -- using the sync handle from step 1
+   and parameters from step 3.
+5. **Receive BIG Sync Established** -- the controller confirms sync
+   with BIS connection handles.
+6. **Setup ISO Data Path** -- configure the data path for each BIS.
+7. **ISO Data flows** -- broadcast audio packets arrive.
+
+If any step fails or is missing, the subsequent steps cannot proceed.
+The most common failure pattern is that **BIG Info is never received**
+(e.g., the periodic advertising data does not contain a BIG, or PA
+sync was lost before BIG Info arrived), which means ``LE BIG Create
+Sync`` is never sent.
+
+Without PAST (Direct PA Sync)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When the receiver scans for and syncs to periodic advertising
+directly (without assistance from a Broadcast Assistant):
+
+**Step 1 -- Create PA sync**::
+
+    < HCI Command: LE Periodic Advertising Create Sync (0x08|0x0044) plen 14  #100 [hci0] 0.100003
+          Options: 0x0000
+          SID: 0x01
+          Adv Address Type: Public (0x00)
+          Adv Address: XX:XX:XX:XX:XX:XX
+          Skip: 0x0000
+          Sync Timeout: 2000 msec (0x00c8)
+          Sync CTE Type: 0x0000
+
+**Step 2 -- PA Sync Established** (sync handle assigned)::
+
+    > HCI Event: LE Meta Event (0x3e) plen 16                 #105 [hci0] 0.150003
+          LE Periodic Advertising Sync Established (0x0e)
+            Status: Success (0x00)
+            Sync Handle: 0x0001
+            Advertising SID: 0x01
+            Advertiser Address Type: Public (0x00)
+            Advertiser Address: XX:XX:XX:XX:XX:XX
+            Advertiser PHY: LE 2M PHY (0x02)
+            Periodic Advertising Interval: 10.000 msec (0x0008)
+            Advertiser Clock Accuracy: 0x05
+
+**Step 3 -- PA Reports** (contain BASE data)::
+
+    > HCI Event: LE Meta Event (0x3e) plen 80                 #110 [hci0] 0.200003
+          LE Periodic Advertising Report (0x0f)
+            Sync Handle: 0x0001
+            ...
+            Service Data: Basic Audio Announcement (0x1851)
+
+**Step 4 -- BIG Info Advertising Report** (critical gate)::
+
+    > HCI Event: LE Meta Event (0x3e) plen 24                 #120 [hci0] 0.300003
+          LE BIG Info Advertising Report (0x22)
+            Sync Handle: 0x0001
+            Number BIS: 2
+            NSE: 4
+            ISO Interval: 10.000 msec (0x0008)
+            BN: 2
+            PTO: 1
+            IRC: 2
+            Maximum PDU: 120
+            SDU Interval: 10000 us
+            Maximum SDU: 120
+            PHY: LE 2M PHY (0x02)
+            Framing: Unframed (0x00)
+            Encryption: 0x00
+
+This event is generated by the controller each time it receives a
+periodic advertising packet that contains BIG Info. It provides all
+parameters the receiver needs to decide whether to sync to the BIG.
+Key fields:
+
+- ``Number BIS`` -- how many BIS streams are available.
+- ``SDU Interval`` and ``Maximum SDU`` -- audio frame timing and size.
+- ``Encryption`` -- whether a Broadcast Code is required (0x01) or
+  not (0x00). If encrypted, the receiver must supply the correct
+  Broadcast Code in ``LE BIG Create Sync``.
+- ``Sync Handle`` -- must match a currently active PA sync.
+
+**Step 5 -- BIG Create Sync** (using sync handle + BIG Info)::
+
+    < HCI Command: LE BIG Create Sync (0x08|0x006b) plen 15  #130 [hci0] 0.400003
+          BIG Handle: 0x00
+          BIG Sync Handle: 0x0001
+          Encryption: Unencrypted (0x00)
+          Broadcast Code: 00000000000000000000000000000000
+          Maximum Number Subevents: 0x00
+          Timeout: 2000 ms (0x00c8)
+          Number of BIS: 2
+          BIS: 0x01
+          BIS: 0x02
+
+**Step 6 -- BIG Sync Established**::
+
+    > HCI Event: LE Meta Event (0x3e) plen 20                 #135 [hci0] 0.450003
+          LE BIG Sync Established (0x1d)
+            Status: Success (0x00)
+            BIG Handle: 0x00
+            Transport Latency: 10000 us
+            NSE: 4
+            BN: 2
+            PTO: 1
+            IRC: 2
+            Maximum PDU: 120
+            ISO Interval: 10.000 msec (0x0008)
+            Connection Handle: 0x0010
+            Connection Handle: 0x0011
+
+On success, the controller assigns BIS connection handles (0x0010,
+0x0011 above). A non-zero Status indicates failure -- common errors:
+
+- ``0x3e`` (Connection Failed to be Established) -- BIG parameters
+  do not match or the BIG is no longer present.
+- ``0x3f`` (Limit Reached) -- controller resources exhausted.
+
+**Step 7 -- Setup ISO Data Path** (for each BIS)::
+
+    < HCI Command: LE Setup ISO Data Path (0x08|0x006e) plen 13  #140 [hci0] 0.500003
+          Connection Handle: 0x0010
+          Data Path Direction: Output (Host to Controller) (0x01)
+          Data Path ID: HCI (0x00)
+
+    < HCI Command: LE Setup ISO Data Path (0x08|0x006e) plen 13  #145 [hci0] 0.550003
+          Connection Handle: 0x0011
+          Data Path Direction: Output (Host to Controller) (0x01)
+          Data Path ID: HCI (0x00)
+
+**Step 8 -- ISO Data flows** on BIS handles::
+
+    > ISO Data: Handle 0x0010 flags 0x02 dlen 124             #150 [hci0] 0.600003
+    > ISO Data: Handle 0x0011 flags 0x02 dlen 124             #151 [hci0] 0.600003
+
+With PAST (Periodic Advertising Sync Transfer)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When a Broadcast Assistant (e.g., a phone) helps a Scan Delegator
+(e.g., a hearing aid) sync to a broadcast, it can transfer the PA
+sync via PAST over an existing ACL connection. This avoids the
+delegator having to scan for and sync to the PA train itself.
+
+The BASS (Broadcast Audio Scan Service) protocol coordinates this:
+
+1. The assistant writes an **Add Source** operation to the delegator's
+   BASS control point with ``PA Sync`` set to ``0x01``
+   (Synchronize via PAST).
+2. The delegator prepares to receive the transfer by setting PAST
+   parameters.
+3. The assistant transfers its PA sync to the delegator.
+4. The delegator receives the PAST event with a sync handle.
+5. From here, the flow continues as in the non-PAST case (PA Reports
+   → BIG Info → BIG Create Sync → etc.).
+
+**BASS Add Source** (assistant writes to delegator, seen in ATT)::
+
+    < ACL Data TX: Handle 64 flags 0x00 dlen 27               #300 [hci0] 1.000003
+          ATT: Write Command (0x52) len 22
+            Handle: 0x0025
+              Data: 04...
+              Opcode: Add Source (0x04)
+                Advertiser Address Type: Public (0x00)
+                Advertiser Address: XX:XX:XX:XX:XX:XX
+                Advertising SID: 0x01
+                PA Sync: Synchronize to PA - PAST (0x01)
+                PA Interval: 0x0008
+                Number of Subgroups: 1
+                  BIS Sync: 0x00000003
+                  Metadata Length: 0
+
+PA Sync values in the Add Source operation:
+
+- ``0x00`` -- Do not synchronize to PA
+- ``0x01`` -- Synchronize to PA, PAST available
+- ``0x02`` -- Synchronize to PA, PAST not available (delegator
+  must scan and sync directly)
+
+**PAST Parameters** (delegator prepares to receive transfer)::
+
+    < HCI Command: LE Periodic Advertising Sync Transfer Parameters (0x08|0x005c) plen 8  #310 [hci0] 1.100003
+          Connection handle: 64
+          Mode: Enabled with report events enabled (0x02)
+          Skip: 0x00
+          Sync timeout: 2000 msec (0x00c8)
+          Sync CTE Type: 0x0000
+
+**PAST Transfer** (assistant sends its PA sync)::
+
+    < HCI Command: LE Periodic Advertising Sync Transfer (0x08|0x005a) plen 6  #320 [hci0] 1.200003
+          Connection handle: 64
+          Service data: 0x0001
+          Sync handle: 1
+
+**PAST Received** (delegator gets the sync handle)::
+
+    > HCI Event: LE Meta Event (0x3e) plen 19                 #325 [hci0] 1.250003
+          LE Periodic Advertising Sync Transfer Received (0x18)
+            Status: Success (0x00)
+            Handle: 64
+            Connection handle: 64
+            Service data: 0x0001
+            Sync handle: 1
+            SID: 0x01
+            Address type: Public (0x00)
+            Address: XX:XX:XX:XX:XX:XX
+            PHY: LE 2M PHY (0x02)
+            Periodic advertising Interval: 10.000
+            Clock Accuracy: 0x05
+
+On success, the delegator now has a PA sync (``Sync handle: 1``) and
+will begin receiving PA Reports and BIG Info events, continuing from
+step 3 of the non-PAST flow above.
+
+.. note::
+
+   **Race condition**: The PAST Parameters command must be sent
+   **before** the assistant sends the PAST Transfer. In BlueZ, the
+   PA sync state in BASS is set after probing completes to avoid
+   the remote sending PAST before the kernel has enabled PAST
+   Parameters on the HCI level.
+
+BIG Sync Teardown
+^^^^^^^^^^^^^^^^^
+
+**Receiver-initiated teardown** -- the receiver terminates its BIG
+sync::
+
+    < HCI Command: LE BIG Terminate Sync (0x08|0x006c) plen 1  #500 [hci0] 5.000003
+          BIG Handle: 0x00
+
+    > HCI Event: Command Complete (0x0e) plen 5               #501 [hci0] 5.001003
+          LE BIG Terminate Sync (0x08|0x006c) ncmd 1
+            Status: Success (0x00)
+            BIG Handle: 0x00
+
+**Broadcaster-initiated teardown** -- the broadcaster terminates its
+BIG, and the receiver gets a BIG Sync Lost event::
+
+    > HCI Event: LE Meta Event (0x3e) plen 2                  #510 [hci0] 6.000003
+          LE BIG Sync Lost (0x1e)
+            BIG Handle: 0x00
+            Reason: Connection Terminated By Local Host (0x16)
+
+The ``Reason`` field indicates why sync was lost:
+
+- ``0x08`` (Connection Timeout) -- BIG packets not received within
+  the sync timeout.
+- ``0x13`` (Remote User Terminated Connection) -- broadcaster stopped
+  the BIG intentionally.
+- ``0x16`` (Connection Terminated By Local Host) -- local controller
+  terminated.
+- ``0x3e`` (Connection Failed to be Established) -- could not
+  establish sync initially.
+
+**Source-side BIG termination** (broadcaster tears down)::
+
+    < HCI Command: LE Terminate BIG (0x08|0x006a) plen 2      #520 [hci0] 7.000003
+          BIG Handle: 0x00
+          Reason: Connection Terminated By Local Host (0x16)
+
+    > HCI Event: LE Meta Event (0x3e) plen 2                  #521 [hci0] 7.001003
+          LE BIG Terminate (0x1c)
+            BIG Handle: 0x00
+            Reason: Connection Terminated By Local Host (0x16)
+
+BIG Sync Failure Diagnosis
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When analyzing a trace where BIG sync fails, check the following in
+order:
+
+1. **Is PA sync established?** -- Look for ``LE Periodic Advertising
+   Sync Established`` with ``Status: Success``. If missing, the
+   receiver never synced to the PA train.
+2. **Are PA Reports arriving?** -- Look for ``LE Periodic Advertising
+   Report`` events. If absent after PA sync, the PA train may have
+   been lost.
+3. **Is BIG Info received?** -- Look for ``LE BIG Info Advertising
+   Report``. **If this event never appears, the BIG does not exist
+   on this PA train**, or the broadcaster has not yet started it.
+   Without BIG Info, ``LE BIG Create Sync`` cannot be sent.
+4. **Is BIG Create Sync sent?** -- If BIG Info was received but
+   ``LE BIG Create Sync`` was never sent, the host-side logic failed
+   to act on the BIG Info (e.g., mismatched codec, encryption
+   mismatch, application-level issue).
+5. **Does BIG Sync Established succeed?** -- Check the ``Status``
+   field. A non-zero status means the controller could not sync to
+   the BIG.
+6. **Is ISO Data Path set up?** -- Look for ``LE Setup ISO Data Path``
+   for each BIS handle from BIG Sync Established.
+7. **Is ISO Data flowing?** -- Look for ``ISO Data`` packets on the
+   BIS handles.
+
+Automating LE Audio Analysis
+------------------------------
+
+**Identify LE Audio activity**::
+
+    grep -n "ASE Control Point\|ASE ID\|State:.*Codec Configured\|State:.*QoS Configured\|State:.*Enabling\|State:.*Streaming\|State:.*Releasing" output.txt
+
+**Track ASE state transitions** for a specific ASE::
+
+    grep -n "ASE ID:" output.txt
+
+Then examine the ``State:`` line following each ASE ID match.
+
+**Check codec configuration**::
+
+    grep -n "Codec: LC3\|Sampling Frequency:\|Frame Duration:\|Frame Length:\|Audio Channel" output.txt
+
+**Verify CIS establishment**::
+
+    grep -n "Set CIG Parameters\|Create CIS\|CIS Established\|Setup ISO Data Path" output.txt
+
+**Detect CIS failures** -- check the Status field after
+``CIS Established``::
+
+    grep -n "CIS Established" output.txt
+
+Then examine the following line for ``Status:``.
+
+**Detect broadcast audio**::
+
+    grep -n "Basic Audio Announcement\|Create BIG\|BIG Complete\|BIG Create Sync\|BIG Sync\|BIG Info\|BIG Terminate\|BIG Sync Lost" output.txt
+
+**Trace BIG Sync receiver flow** -- verify each prerequisite step::
+
+    grep -n "Periodic Advertising Create Sync\|Periodic Advertising Sync Established\|BIG Info Advertising Report\|BIG Create Sync\|BIG Sync Established\|BIG Sync Lost\|BIG Terminate" output.txt
+
+**Detect PAST-based sync** -- check for Periodic Advertising Sync
+Transfer::
+
+    grep -n "Sync Transfer Parameters\|Sync Transfer (0x08\|PAST Received\|PA Sync:.*PAST\|Add Source" output.txt
+
+**Check BIG Info arrival** -- the critical gate for BIG sync. If this
+is absent, the receiver has no BIG to sync to::
+
+    grep -n "BIG Info Advertising Report" output.txt
+
+**Full LE Audio diagnosis pattern**:
+
+*Unicast (CIS) flow:*
+
+1. Find PACS reads -- verify codec compatibility between devices
+2. Find ASE Control Point writes -- trace the Config Codec → Config
+   QoS → Enable sequence
+3. Find ASE state notifications -- verify each transition succeeds
+4. Find CIG Parameters and CIS creation -- verify HCI-level setup
+5. Find ``CIS Established`` -- check Status for success
+6. Find ``Setup ISO Data Path`` -- verify data path configuration
+7. Find ISO Data packets -- confirm audio is flowing
+8. On failure, check ASE Control Point notification responses for
+   error codes (Response Code and Response Reason fields)
+
+*Broadcast (BIG) receiver flow:*
+
+1. Find ``Periodic Advertising Create Sync`` or ``PAST Received`` --
+   how did PA sync start?
+2. Find ``Periodic Advertising Sync Established`` or
+   ``PAST Received`` with ``Status: Success`` -- is PA synced?
+3. Find ``Periodic Advertising Report`` with
+   ``Basic Audio Announcement`` -- is BASE data arriving?
+4. Find ``BIG Info Advertising Report`` -- **critical**: does the BIG
+   exist? If missing, the BIG cannot be synced.
+5. Find ``BIG Create Sync`` -- did the host request BIG sync?
+6. Find ``BIG Sync Established`` -- check ``Status`` for success.
+7. Find ``Setup ISO Data Path`` for each BIS handle.
+8. Find ``ISO Data`` on BIS handles -- confirm audio is flowing.
+9. On failure, check for ``BIG Sync Lost`` and examine ``Reason``.
diff --git a/doc/btmon.rst b/doc/btmon.rst
index 657f33ff19f1..66650752c490 100644
--- a/doc/btmon.rst
+++ b/doc/btmon.rst
@@ -1567,660 +1567,6 @@ channel, note the Source CID and Destination CID from the Connection
 Request/Response pair. Then search for those CIDs in subsequent data
 frames.
 
-LE AUDIO PROTOCOL FLOW
-=======================
-
-LE Audio uses a multi-layer protocol stack visible in btmon traces.
-The setup sequence involves ATT operations on specific GATT
-characteristics (PACS, ASCS) followed by HCI-level CIS/BIG
-management. btmon fully decodes all layers.
-
-PACS: Published Audio Capabilities
-------------------------------------
-
-Before audio streaming begins, devices exchange codec capabilities
-via the Published Audio Capabilities Service (PACS). The client reads
-PACS characteristics to learn what the remote device supports.
-
-**Sink PAC read** (remote device's receive capabilities)::
-
-    < ACL Data TX: Handle 2048 flags 0x00 dlen 7    #550 [hci0] 0.824003
-          ATT: Read Request (0x0a) len 2
-            Handle: 0x0075
-
-    > ACL Data RX: Handle 2048 flags 0x02 dlen 30   #552 [hci0] 0.886556
-          ATT: Read Response (0x0b) len 25
-            Handle: 0x0075
-              Number of PAC(s): 1
-              Codec: LC3 (0x06)
-              Codec Specific Capabilities: #0
-                Sampling Frequency: 8000 Hz 16000 Hz 24000 Hz 32000 Hz 48000 Hz
-                Frame Duration: 7.5 ms 10 ms
-                Audio Channel Counts: 1
-                Frame Length: 26 - 240
-
-The PAC record shows codec capabilities using LTV (Length-Type-Value)
-encoding. Key fields:
-
-- **Codec** -- ``LC3 (0x06)`` is the mandatory LE Audio codec
-- **Sampling Frequency** -- Supported sample rates (bitmask)
-- **Frame Duration** -- Supported frame durations (7.5 ms and/or 10 ms)
-- **Audio Channel Counts** -- Supported channel counts
-- **Frame Length** -- Min and max octets per codec frame
-
-**Audio Locations** (channel assignment)::
-
-    > ACL Data RX: Handle 2048 flags 0x02 dlen 9    #554 [hci0] 0.948003
-          ATT: Read Response (0x0b) len 4
-            Handle: 0x0077
-              Location: Front Left
-
-**Available Audio Contexts** (current use cases)::
-
-    > ACL Data RX: Handle 2048 flags 0x02 dlen 9    #558 [hci0] 1.012556
-          ATT: Read Response (0x0b) len 4
-            Handle: 0x007b
-              Sink Context: Media Conversational
-              Source Context: Unspecified
-
-ASCS: Audio Stream Control
-----------------------------
-
-The Audio Stream Control Service (ASCS) manages the ASE (Audio Stream
-Endpoint) state machine. Each ASE transitions through a defined set
-of states as streaming is set up and torn down.
-
-**ASE State Machine**::
-
-    Idle ──► Codec Configured ──► QoS Configured ──► Enabling ──► Streaming
-                                                                      │
-    Idle ◄── Releasing ◄──────── Disabling ◄─────────────────────────┘
-
-**ASE Status notification** (state change)::
-
-    > ACL Data RX: Handle 2048 flags 0x02 dlen 20   #580 [hci0] 1.456003
-          ATT: Handle Value Notification (0x1b) len 15
-            Handle: 0x0088
-              ASE ID: 0x01
-              State: Codec Configured (0x01)
-                Framing: Unframed PDUs supported (0x00)
-                PHY: 0x02
-                  LE 2M PHY (0x02)
-                RTN: 2
-                Max Transport Latency: 10
-                Presentation Delay Min: 20000 us
-                Presentation Delay Max: 40000 us
-                Preferred Presentation Delay Min: 20000 us
-                Preferred Presentation Delay Max: 40000 us
-                Codec: LC3 (0x06)
-                  Sampling Frequency: 48000 Hz
-                  Frame Duration: 10 ms
-                  Audio Channel Allocation: Front Left
-                  Frame Length: 120
-
-**ASE Control Point operations** drive state transitions. The client
-writes to the ASE Control Point characteristic to issue commands::
-
-    < ACL Data TX: Handle 2048 flags 0x00 dlen 25   #582 [hci0] 1.518003
-          ATT: Write Request (0x12) len 20
-            Handle: 0x008b
-              ASE Control Point: Config Codec (0x01)
-                ASE ID: 0x01
-                Target Latency: Low Latency (0x01)
-                PHY: LE 2M PHY
-                Codec: LC3 (0x06)
-                  Sampling Frequency: 48000 Hz
-                  Frame Duration: 10 ms
-                  Audio Channel Allocation: Front Left
-                  Frame Length: 120
-
-ASE Control Point commands:
-
-.. list-table::
-   :header-rows: 1
-   :widths: 10 25 65
-
-   * - Opcode
-     - Command
-     - Purpose
-   * - 0x01
-     - Config Codec
-     - Select codec and parameters (Idle → Codec Configured)
-   * - 0x02
-     - Config QoS
-     - Set CIG/CIS IDs and QoS params (Codec Configured → QoS Configured)
-   * - 0x03
-     - Enable
-     - Start ASE with metadata (QoS Configured → Enabling)
-   * - 0x04
-     - Receiver Start Ready
-     - Signal receiver readiness (Enabling → Streaming, server-side)
-   * - 0x05
-     - Disable
-     - Stop streaming (Streaming → Disabling)
-   * - 0x06
-     - Receiver Stop Ready
-     - Signal receiver stopped
-   * - 0x07
-     - Update Metadata
-     - Change metadata during streaming
-   * - 0x08
-     - Release
-     - Tear down ASE (any → Releasing → Idle)
-
-CIS Setup and Teardown
-------------------------
-
-After ASE QoS Configuration, the host creates Connected Isochronous
-Streams (CIS) at the HCI level.
-
-**CIG Parameters** (configure the CIS group)::
-
-    < HCI Command: LE Set CIG Parameters (0x08|0x0062) plen 26  #590 [hci0] 1.624003
-          CIG ID: 0x00
-          Central to Peripheral SDU Interval: 10000 us
-          Peripheral to Central SDU Interval: 10000 us
-          SCA: 0x00
-          Packing: Sequential (0x00)
-          Framing: Unframed (0x00)
-          Central to Peripheral Max Latency: 10 ms
-          Peripheral to Central Max Latency: 10 ms
-          Number of CIS: 1
-          CIS ID: 0x00
-          Central to Peripheral Max SDU: 120
-          Peripheral to Central Max SDU: 0
-          Central to Peripheral PHY: LE 2M PHY
-          Peripheral to Central PHY: LE 2M PHY
-          Central to Peripheral RTN: 2
-          Peripheral to Central RTN: 2
-
-    > HCI Event: Command Complete (0x0e) plen 8              #592 [hci0] 1.624556
-          LE Set CIG Parameters (0x08|0x0062) ncmd 1
-            Status: Success (0x00)
-            CIG ID: 0x00
-            Number of Handles: 1
-            Connection Handle: 2064
-
-**CIS Creation**::
-
-    < HCI Command: LE Create CIS (0x08|0x0064) plen 9       #594 [hci0] 1.688003
-          Number of CIS: 1
-          CIS Handle: 2064
-          ACL Handle: 2048
-
-    > HCI Event: LE Meta Event (0x3e) plen 29                #596 [hci0] 1.756556
-          LE CIS Established (0x19)
-            Status: Success (0x00)
-            Connection Handle: 2064
-            CIG Sync Delay: 5000 us
-            CIS Sync Delay: 5000 us
-            Central to Peripheral Latency: 10000 us
-            Peripheral to Central Latency: 10000 us
-            Central to Peripheral PHY: LE 2M PHY
-            Peripheral to Central PHY: LE 2M PHY
-            NSE: 3
-            Central to Peripheral BN: 1
-            Peripheral to Central BN: 0
-            Central to Peripheral FT: 2
-            Peripheral to Central FT: 2
-            Max PDU C to P: 120
-            Max PDU P to C: 0
-            ISO Interval: 10.00 msec (0x0008)
-
-Note that the CIS Handle (2064) is different from the ACL Handle
-(2048). CIS data packets use the CIS handle.
-
-**ISO Data Path Setup**::
-
-    < HCI Command: LE Setup ISO Data Path (0x08|0x006e) plen 13  #598 [hci0] 1.820003
-          Handle: 2064
-          Data Path Direction: Input (Host to Controller) (0x00)
-          Data Path ID: HCI (0x00)
-          Coding Format: LC3 (0x06)
-          Company ID: 0x0000
-          Vendor Codec ID: 0x0000
-          Controller Delay: 0 us
-
-After this, ISO data packets flow on the CIS handle::
-
-    < ISO Data TS: Handle 2064 flags 0x02 dlen 124  #600 [hci0] 1.884003
-
-Broadcast Audio (BIG)
-----------------------
-
-Broadcast Isochronous Streams use BIG (Broadcast Isochronous Group)
-instead of CIS. The setup involves periodic advertising with BASE
-(Broadcast Audio Source Endpoint) announcements.
-
-**BASE announcement** (in periodic advertising data)::
-
-    > HCI Event: LE Meta Event (0x3e) plen 80                #200 [hci0] 0.500003
-          LE Periodic Advertising Report (0x0f)
-            ...
-            Service Data: Basic Audio Announcement (0x1851)
-              Presentation Delay: 40000 us
-              Number of Subgroups: 1
-                Number of BIS: 2
-                Codec: LC3 (0x06)
-                  Sampling Frequency: 48000 Hz
-                  Frame Duration: 10 ms
-                  Frame Length: 120
-                BIS #1
-                  Audio Channel Allocation: Front Left
-                BIS #2
-                  Audio Channel Allocation: Front Right
-
-**BIG creation** (source side)::
-
-    < HCI Command: LE Create BIG (0x08|0x0068) plen 31      #210 [hci0] 0.600003
-          BIG Handle: 0x00
-          Advertising Handle: 0x01
-          Number of BIS: 2
-          SDU Interval: 10000 us
-          Max SDU: 120
-          Max Latency: 10 ms
-          RTN: 2
-          PHY: LE 2M PHY
-          Packing: Sequential (0x00)
-          Framing: Unframed (0x00)
-          Encryption: Unencrypted (0x00)
-
-**BIG sync** (receiver side)::
-
-    < HCI Command: LE BIG Create Sync (0x08|0x006b) plen 15  #220 [hci0] 0.700003
-          BIG Handle: 0x00
-          Sync Handle: 0x0001
-          Encryption: Unencrypted (0x00)
-          Number of BIS: 2
-          BIS: 0x01
-          BIS: 0x02
-
-BIG Sync Receiver Flow
-~~~~~~~~~~~~~~~~~~~~~~
-
-A receiver must complete a specific sequence of steps before it can
-receive broadcast audio. The critical prerequisite chain is:
-
-1. **Synchronize to periodic advertising** -- the receiver must first
-   discover and sync to the broadcaster's periodic advertising train.
-2. **Receive PA Reports with BASE** -- the periodic advertising data
-   contains the BASE (Broadcast Audio Source Endpoint) structure
-   describing the broadcast's codec configuration.
-3. **Receive BIG Info Advertising Report** -- this event tells the
-   receiver that a BIG exists on the periodic advertising train and
-   provides its parameters (number of BIS, encryption, SDU interval,
-   etc.). **This is the critical gate**: without receiving BIG Info,
-   the receiver cannot issue ``LE BIG Create Sync``.
-4. **Issue LE BIG Create Sync** -- using the sync handle from step 1
-   and parameters from step 3.
-5. **Receive BIG Sync Established** -- the controller confirms sync
-   with BIS connection handles.
-6. **Setup ISO Data Path** -- configure the data path for each BIS.
-7. **ISO Data flows** -- broadcast audio packets arrive.
-
-If any step fails or is missing, the subsequent steps cannot proceed.
-The most common failure pattern is that **BIG Info is never received**
-(e.g., the periodic advertising data does not contain a BIG, or PA
-sync was lost before BIG Info arrived), which means ``LE BIG Create
-Sync`` is never sent.
-
-Without PAST (Direct PA Sync)
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-When the receiver scans for and syncs to periodic advertising
-directly (without assistance from a Broadcast Assistant):
-
-**Step 1 -- Create PA sync**::
-
-    < HCI Command: LE Periodic Advertising Create Sync (0x08|0x0044) plen 14  #100 [hci0] 0.100003
-          Options: 0x0000
-          SID: 0x01
-          Adv Address Type: Public (0x00)
-          Adv Address: XX:XX:XX:XX:XX:XX
-          Skip: 0x0000
-          Sync Timeout: 2000 msec (0x00c8)
-          Sync CTE Type: 0x0000
-
-**Step 2 -- PA Sync Established** (sync handle assigned)::
-
-    > HCI Event: LE Meta Event (0x3e) plen 16                 #105 [hci0] 0.150003
-          LE Periodic Advertising Sync Established (0x0e)
-            Status: Success (0x00)
-            Sync Handle: 0x0001
-            Advertising SID: 0x01
-            Advertiser Address Type: Public (0x00)
-            Advertiser Address: XX:XX:XX:XX:XX:XX
-            Advertiser PHY: LE 2M PHY (0x02)
-            Periodic Advertising Interval: 10.000 msec (0x0008)
-            Advertiser Clock Accuracy: 0x05
-
-**Step 3 -- PA Reports** (contain BASE data)::
-
-    > HCI Event: LE Meta Event (0x3e) plen 80                 #110 [hci0] 0.200003
-          LE Periodic Advertising Report (0x0f)
-            Sync Handle: 0x0001
-            ...
-            Service Data: Basic Audio Announcement (0x1851)
-
-**Step 4 -- BIG Info Advertising Report** (critical gate)::
-
-    > HCI Event: LE Meta Event (0x3e) plen 24                 #120 [hci0] 0.300003
-          LE BIG Info Advertising Report (0x22)
-            Sync Handle: 0x0001
-            Number BIS: 2
-            NSE: 4
-            ISO Interval: 10.000 msec (0x0008)
-            BN: 2
-            PTO: 1
-            IRC: 2
-            Maximum PDU: 120
-            SDU Interval: 10000 us
-            Maximum SDU: 120
-            PHY: LE 2M PHY (0x02)
-            Framing: Unframed (0x00)
-            Encryption: 0x00
-
-This event is generated by the controller each time it receives a
-periodic advertising packet that contains BIG Info. It provides all
-parameters the receiver needs to decide whether to sync to the BIG.
-Key fields:
-
-- ``Number BIS`` -- how many BIS streams are available.
-- ``SDU Interval`` and ``Maximum SDU`` -- audio frame timing and size.
-- ``Encryption`` -- whether a Broadcast Code is required (0x01) or
-  not (0x00). If encrypted, the receiver must supply the correct
-  Broadcast Code in ``LE BIG Create Sync``.
-- ``Sync Handle`` -- must match a currently active PA sync.
-
-**Step 5 -- BIG Create Sync** (using sync handle + BIG Info)::
-
-    < HCI Command: LE BIG Create Sync (0x08|0x006b) plen 15  #130 [hci0] 0.400003
-          BIG Handle: 0x00
-          BIG Sync Handle: 0x0001
-          Encryption: Unencrypted (0x00)
-          Broadcast Code: 00000000000000000000000000000000
-          Maximum Number Subevents: 0x00
-          Timeout: 2000 ms (0x00c8)
-          Number of BIS: 2
-          BIS: 0x01
-          BIS: 0x02
-
-**Step 6 -- BIG Sync Established**::
-
-    > HCI Event: LE Meta Event (0x3e) plen 20                 #135 [hci0] 0.450003
-          LE BIG Sync Established (0x1d)
-            Status: Success (0x00)
-            BIG Handle: 0x00
-            Transport Latency: 10000 us
-            NSE: 4
-            BN: 2
-            PTO: 1
-            IRC: 2
-            Maximum PDU: 120
-            ISO Interval: 10.000 msec (0x0008)
-            Connection Handle: 0x0010
-            Connection Handle: 0x0011
-
-On success, the controller assigns BIS connection handles (0x0010,
-0x0011 above). A non-zero Status indicates failure -- common errors:
-
-- ``0x3e`` (Connection Failed to be Established) -- BIG parameters
-  do not match or the BIG is no longer present.
-- ``0x3f`` (Limit Reached) -- controller resources exhausted.
-
-**Step 7 -- Setup ISO Data Path** (for each BIS)::
-
-    < HCI Command: LE Setup ISO Data Path (0x08|0x006e) plen 13  #140 [hci0] 0.500003
-          Connection Handle: 0x0010
-          Data Path Direction: Output (Host to Controller) (0x01)
-          Data Path ID: HCI (0x00)
-
-    < HCI Command: LE Setup ISO Data Path (0x08|0x006e) plen 13  #145 [hci0] 0.550003
-          Connection Handle: 0x0011
-          Data Path Direction: Output (Host to Controller) (0x01)
-          Data Path ID: HCI (0x00)
-
-**Step 8 -- ISO Data flows** on BIS handles::
-
-    > ISO Data: Handle 0x0010 flags 0x02 dlen 124             #150 [hci0] 0.600003
-    > ISO Data: Handle 0x0011 flags 0x02 dlen 124             #151 [hci0] 0.600003
-
-With PAST (Periodic Advertising Sync Transfer)
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-When a Broadcast Assistant (e.g., a phone) helps a Scan Delegator
-(e.g., a hearing aid) sync to a broadcast, it can transfer the PA
-sync via PAST over an existing ACL connection. This avoids the
-delegator having to scan for and sync to the PA train itself.
-
-The BASS (Broadcast Audio Scan Service) protocol coordinates this:
-
-1. The assistant writes an **Add Source** operation to the delegator's
-   BASS control point with ``PA Sync`` set to ``0x01``
-   (Synchronize via PAST).
-2. The delegator prepares to receive the transfer by setting PAST
-   parameters.
-3. The assistant transfers its PA sync to the delegator.
-4. The delegator receives the PAST event with a sync handle.
-5. From here, the flow continues as in the non-PAST case (PA Reports
-   → BIG Info → BIG Create Sync → etc.).
-
-**BASS Add Source** (assistant writes to delegator, seen in ATT)::
-
-    < ACL Data TX: Handle 64 flags 0x00 dlen 27               #300 [hci0] 1.000003
-          ATT: Write Command (0x52) len 22
-            Handle: 0x0025
-              Data: 04...
-              Opcode: Add Source (0x04)
-                Advertiser Address Type: Public (0x00)
-                Advertiser Address: XX:XX:XX:XX:XX:XX
-                Advertising SID: 0x01
-                PA Sync: Synchronize to PA - PAST (0x01)
-                PA Interval: 0x0008
-                Number of Subgroups: 1
-                  BIS Sync: 0x00000003
-                  Metadata Length: 0
-
-PA Sync values in the Add Source operation:
-
-- ``0x00`` -- Do not synchronize to PA
-- ``0x01`` -- Synchronize to PA, PAST available
-- ``0x02`` -- Synchronize to PA, PAST not available (delegator
-  must scan and sync directly)
-
-**PAST Parameters** (delegator prepares to receive transfer)::
-
-    < HCI Command: LE Periodic Advertising Sync Transfer Parameters (0x08|0x005c) plen 8  #310 [hci0] 1.100003
-          Connection handle: 64
-          Mode: Enabled with report events enabled (0x02)
-          Skip: 0x00
-          Sync timeout: 2000 msec (0x00c8)
-          Sync CTE Type: 0x0000
-
-**PAST Transfer** (assistant sends its PA sync)::
-
-    < HCI Command: LE Periodic Advertising Sync Transfer (0x08|0x005a) plen 6  #320 [hci0] 1.200003
-          Connection handle: 64
-          Service data: 0x0001
-          Sync handle: 1
-
-**PAST Received** (delegator gets the sync handle)::
-
-    > HCI Event: LE Meta Event (0x3e) plen 19                 #325 [hci0] 1.250003
-          LE Periodic Advertising Sync Transfer Received (0x18)
-            Status: Success (0x00)
-            Handle: 64
-            Connection handle: 64
-            Service data: 0x0001
-            Sync handle: 1
-            SID: 0x01
-            Address type: Public (0x00)
-            Address: XX:XX:XX:XX:XX:XX
-            PHY: LE 2M PHY (0x02)
-            Periodic advertising Interval: 10.000
-            Clock Accuracy: 0x05
-
-On success, the delegator now has a PA sync (``Sync handle: 1``) and
-will begin receiving PA Reports and BIG Info events, continuing from
-step 3 of the non-PAST flow above.
-
-.. note::
-
-   **Race condition**: The PAST Parameters command must be sent
-   **before** the assistant sends the PAST Transfer. In BlueZ, the
-   PA sync state in BASS is set after probing completes to avoid
-   the remote sending PAST before the kernel has enabled PAST
-   Parameters on the HCI level.
-
-BIG Sync Teardown
-^^^^^^^^^^^^^^^^^
-
-**Receiver-initiated teardown** -- the receiver terminates its BIG
-sync::
-
-    < HCI Command: LE BIG Terminate Sync (0x08|0x006c) plen 1  #500 [hci0] 5.000003
-          BIG Handle: 0x00
-
-    > HCI Event: Command Complete (0x0e) plen 5               #501 [hci0] 5.001003
-          LE BIG Terminate Sync (0x08|0x006c) ncmd 1
-            Status: Success (0x00)
-            BIG Handle: 0x00
-
-**Broadcaster-initiated teardown** -- the broadcaster terminates its
-BIG, and the receiver gets a BIG Sync Lost event::
-
-    > HCI Event: LE Meta Event (0x3e) plen 2                  #510 [hci0] 6.000003
-          LE BIG Sync Lost (0x1e)
-            BIG Handle: 0x00
-            Reason: Connection Terminated By Local Host (0x16)
-
-The ``Reason`` field indicates why sync was lost:
-
-- ``0x08`` (Connection Timeout) -- BIG packets not received within
-  the sync timeout.
-- ``0x13`` (Remote User Terminated Connection) -- broadcaster stopped
-  the BIG intentionally.
-- ``0x16`` (Connection Terminated By Local Host) -- local controller
-  terminated.
-- ``0x3e`` (Connection Failed to be Established) -- could not
-  establish sync initially.
-
-**Source-side BIG termination** (broadcaster tears down)::
-
-    < HCI Command: LE Terminate BIG (0x08|0x006a) plen 2      #520 [hci0] 7.000003
-          BIG Handle: 0x00
-          Reason: Connection Terminated By Local Host (0x16)
-
-    > HCI Event: LE Meta Event (0x3e) plen 2                  #521 [hci0] 7.001003
-          LE BIG Terminate (0x1c)
-            BIG Handle: 0x00
-            Reason: Connection Terminated By Local Host (0x16)
-
-BIG Sync Failure Diagnosis
-^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-When analyzing a trace where BIG sync fails, check the following in
-order:
-
-1. **Is PA sync established?** -- Look for ``LE Periodic Advertising
-   Sync Established`` with ``Status: Success``. If missing, the
-   receiver never synced to the PA train.
-2. **Are PA Reports arriving?** -- Look for ``LE Periodic Advertising
-   Report`` events. If absent after PA sync, the PA train may have
-   been lost.
-3. **Is BIG Info received?** -- Look for ``LE BIG Info Advertising
-   Report``. **If this event never appears, the BIG does not exist
-   on this PA train**, or the broadcaster has not yet started it.
-   Without BIG Info, ``LE BIG Create Sync`` cannot be sent.
-4. **Is BIG Create Sync sent?** -- If BIG Info was received but
-   ``LE BIG Create Sync`` was never sent, the host-side logic failed
-   to act on the BIG Info (e.g., mismatched codec, encryption
-   mismatch, application-level issue).
-5. **Does BIG Sync Established succeed?** -- Check the ``Status``
-   field. A non-zero status means the controller could not sync to
-   the BIG.
-6. **Is ISO Data Path set up?** -- Look for ``LE Setup ISO Data Path``
-   for each BIS handle from BIG Sync Established.
-7. **Is ISO Data flowing?** -- Look for ``ISO Data`` packets on the
-   BIS handles.
-
-Automating LE Audio Analysis
-------------------------------
-
-**Identify LE Audio activity**::
-
-    grep -n "ASE Control Point\|ASE ID\|State:.*Codec Configured\|State:.*QoS Configured\|State:.*Enabling\|State:.*Streaming\|State:.*Releasing" output.txt
-
-**Track ASE state transitions** for a specific ASE::
-
-    grep -n "ASE ID:" output.txt
-
-Then examine the ``State:`` line following each ASE ID match.
-
-**Check codec configuration**::
-
-    grep -n "Codec: LC3\|Sampling Frequency:\|Frame Duration:\|Frame Length:\|Audio Channel" output.txt
-
-**Verify CIS establishment**::
-
-    grep -n "Set CIG Parameters\|Create CIS\|CIS Established\|Setup ISO Data Path" output.txt
-
-**Detect CIS failures** -- check the Status field after
-``CIS Established``::
-
-    grep -n "CIS Established" output.txt
-
-Then examine the following line for ``Status:``.
-
-**Detect broadcast audio**::
-
-    grep -n "Basic Audio Announcement\|Create BIG\|BIG Complete\|BIG Create Sync\|BIG Sync\|BIG Info\|BIG Terminate\|BIG Sync Lost" output.txt
-
-**Trace BIG Sync receiver flow** -- verify each prerequisite step::
-
-    grep -n "Periodic Advertising Create Sync\|Periodic Advertising Sync Established\|BIG Info Advertising Report\|BIG Create Sync\|BIG Sync Established\|BIG Sync Lost\|BIG Terminate" output.txt
-
-**Detect PAST-based sync** -- check for Periodic Advertising Sync
-Transfer::
-
-    grep -n "Sync Transfer Parameters\|Sync Transfer (0x08\|PAST Received\|PA Sync:.*PAST\|Add Source" output.txt
-
-**Check BIG Info arrival** -- the critical gate for BIG sync. If this
-is absent, the receiver has no BIG to sync to::
-
-    grep -n "BIG Info Advertising Report" output.txt
-
-**Full LE Audio diagnosis pattern**:
-
-*Unicast (CIS) flow:*
-
-1. Find PACS reads -- verify codec compatibility between devices
-2. Find ASE Control Point writes -- trace the Config Codec → Config
-   QoS → Enable sequence
-3. Find ASE state notifications -- verify each transition succeeds
-4. Find CIG Parameters and CIS creation -- verify HCI-level setup
-5. Find ``CIS Established`` -- check Status for success
-6. Find ``Setup ISO Data Path`` -- verify data path configuration
-7. Find ISO Data packets -- confirm audio is flowing
-8. On failure, check ASE Control Point notification responses for
-   error codes (Response Code and Response Reason fields)
-
-*Broadcast (BIG) receiver flow:*
-
-1. Find ``Periodic Advertising Create Sync`` or ``PAST Received`` --
-   how did PA sync start?
-2. Find ``Periodic Advertising Sync Established`` or
-   ``PAST Received`` with ``Status: Success`` -- is PA synced?
-3. Find ``Periodic Advertising Report`` with
-   ``Basic Audio Announcement`` -- is BASE data arriving?
-4. Find ``BIG Info Advertising Report`` -- **critical**: does the BIG
-   exist? If missing, the BIG cannot be synced.
-5. Find ``BIG Create Sync`` -- did the host request BIG sync?
-6. Find ``BIG Sync Established`` -- check ``Status`` for success.
-7. Find ``Setup ISO Data Path`` for each BIS handle.
-8. Find ``ISO Data`` on BIS handles -- confirm audio is flowing.
-9. On failure, check for ``BIG Sync Lost`` and examine ``Reason``.
-
 PROTOCOL ERROR CODES
 =====================
 
@@ -2405,6 +1751,8 @@ Errors often cascade across layers. Common patterns:
 PROTOCOL FLOWS
 ===============
 
+.. include:: btmon-le-audio.rst
+
 .. include:: btmon-advertising.rst
 
 EXAMPLES
-- 
2.53.0