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Bluetooth: Remove CONFIG_BT_BUF_ACL_RX_COUNT #96912

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Bluetooth: Remove CONFIG_BT_BUF_ACL_RX_COUNT #96912

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4cdb6ee
Bluetooth: Remove CONFIG_BT_BUF_ACL_RX_COUNT
Thalley Oct 2, 2025
a71f4a9
doc: releases: Add note about CONFIG_BT_BUF_ACL_RX_COUNT
Thalley Oct 2, 2025
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1 change: 1 addition & 0 deletions doc/releases/release-notes-4.3.rst
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Expand Up @@ -58,6 +58,7 @@ Removed APIs and options
PSA Crypto API is now the recommended cryptographic library for Zephyr.
* The legacy pipe object API was removed. Use the new pipe API instead.
* ``bt_le_set_auto_conn``
* ``CONFIG_BT_BUF_ACL_RX_COUNT``

Deprecated APIs and options
===========================
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23 changes: 8 additions & 15 deletions include/zephyr/bluetooth/buf.h
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Expand Up @@ -144,27 +144,20 @@ static inline enum bt_buf_type bt_buf_type_from_h4(uint8_t h4_type, enum bt_buf_
#define BT_BUF_ACL_RX_COUNT_MAX 65535

#if defined(CONFIG_BT_CONN) && defined(CONFIG_BT_HCI_HOST)
/* The host needs more ACL buffers than maximum ACL links. This is because of
* the way we re-assemble ACL packets into L2CAP PDUs.
*
* We keep around the first buffer (that comes from the driver) to do
* re-assembly into, and if all links are re-assembling, there will be no buffer
* available for the HCI driver to allocate from.
*
* TODO: When CONFIG_BT_BUF_ACL_RX_COUNT is removed,
* remove the MAX and only keep the 1.
*/
/* The host needs more ACL buffers than maximum ACL links. This is because of
* the way we re-assemble ACL packets into L2CAP PDUs.
*
* We keep around the first buffer (that comes from the driver) to do
* re-assembly into, and if all links are re-assembling, there will be no buffer
* available for the HCI driver to allocate from.
*/
#define BT_BUF_ACL_RX_COUNT_EXTRA CONFIG_BT_BUF_ACL_RX_COUNT_EXTRA
#define BT_BUF_ACL_RX_COUNT (MAX(CONFIG_BT_BUF_ACL_RX_COUNT, 1) + BT_BUF_ACL_RX_COUNT_EXTRA)
#define BT_BUF_ACL_RX_COUNT (1 + BT_BUF_ACL_RX_COUNT_EXTRA)
#else
#define BT_BUF_ACL_RX_COUNT_EXTRA 0
#define BT_BUF_ACL_RX_COUNT 0
#endif /* CONFIG_BT_CONN && CONFIG_BT_HCI_HOST */

#if defined(CONFIG_BT_BUF_ACL_RX_COUNT) && CONFIG_BT_BUF_ACL_RX_COUNT > 0
#warning "CONFIG_BT_BUF_ACL_RX_COUNT is deprecated, see Zephyr 4.1 migration guide"
#endif /* CONFIG_BT_BUF_ACL_RX_COUNT && CONFIG_BT_BUF_ACL_RX_COUNT > 0 */

BUILD_ASSERT(BT_BUF_ACL_RX_COUNT <= BT_BUF_ACL_RX_COUNT_MAX,
"Maximum number of ACL RX buffer is 65535, reduce CONFIG_BT_BUF_ACL_RX_COUNT_EXTRA");

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21 changes: 0 additions & 21 deletions subsys/bluetooth/common/Kconfig
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Expand Up @@ -102,27 +102,6 @@ config BT_BUF_ACL_RX_COUNT_EXTRA
connection and uses one Rx buffer across all connections to receive a
fragment from the Controller.

config BT_BUF_ACL_RX_COUNT
int "[DEPRECATED] Number of incoming ACL data buffers"
default 0
range 0 256
help
Number or incoming ACL data buffers sent from the Controller to the
Host.
In a combined Host and Controller build the buffers are shared and
therefore Controller to Host flow control is not needed.

In a Host only build with Controller to Host flow control enabled
the Host will inform the Controller about the maximum number of
buffers by setting this value in the Host Buffer Size command.

When Controller to Host flow control is not enabled the Controller
can assume that the Host has infinite amount of buffers.

For both configurations, there is an additional requirement that is
enforced by a build-time check: BT_BUF_ACL_RX_COUNT needs to be at
least one greater than BT_MAX_CONN.

config BT_BUF_EVT_RX_SIZE
int "Maximum supported HCI Event buffer length"
default $(UINT8_MAX) if (BT_EXT_ADV && BT_OBSERVER) || BT_PER_ADV_SYNC || BT_DF_CONNECTION_CTE_RX || BT_CLASSIC || BT_CHANNEL_SOUNDING || BT_LE_EXTENDED_FEAT_SET
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