From b2dbd56db2a76efd326bbea2a5d65804488da7f3 Mon Sep 17 00:00:00 2001
From: Mikey Sklar <mikeysklar@gmail.com>
Date: Sun, 23 Aug 2026 09:17:44 -0700
Subject: [PATCH] zephyr-cp/_bleio: don't let an unsupported Tx power command
 block advertising

common_hal_bleio_adapter_start_advertising() called set_tx_power()
unconditionally before bt_le_adv_start(). That sends
BT_HCI_OP_VS_WRITE_TX_POWER_LEVEL (0xfc0e), a Zephyr vendor-specific
command rather than a Bluetooth spec one. Controllers that do not
implement Zephyr's VS extensions reject it, and the resulting error
aborted start_advertising() before advertising was ever started, so
those controllers could not advertise at all.

On a SiWx917-DK2605A, which has its own vendor command at 0xfc06 for RF
power:

    <wrn> bt_hci_core: opcode 0xfc0e status 0x01   (Unknown HCI Command)
    OSError: [Errno 5] Input/output error

Split the command into a non-raising _try_set_tx_power(). The public
common_hal_bleio_adapter_set_tx_power() still raises, so an explicit
adapter.tx_power assignment fails loudly, but start_advertising() treats
it as best-effort and continues.
---
 ports/zephyr-cp/common-hal/_bleio/Adapter.c | 23 +++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/ports/zephyr-cp/common-hal/_bleio/Adapter.c b/ports/zephyr-cp/common-hal/_bleio/Adapter.c
index ac2b1948eb7..cfa3c82dc96 100644
--- a/ports/zephyr-cp/common-hal/_bleio/Adapter.c
+++ b/ports/zephyr-cp/common-hal/_bleio/Adapter.c
@@ -328,13 +328,16 @@ mp_int_t common_hal_bleio_adapter_get_tx_power(bleio_adapter_obj_t *self) {
     return power;
 }
 
-void common_hal_bleio_adapter_set_tx_power(bleio_adapter_obj_t *self, mp_int_t tx_power) {
+// Returns a Zephyr error code rather than raising, so callers can treat setting
+// Tx power as best-effort. BT_HCI_OP_VS_WRITE_TX_POWER_LEVEL is a Zephyr
+// vendor-specific command that not every controller implements.
+static int _try_set_tx_power(mp_int_t tx_power) {
     struct bt_hci_cp_vs_write_tx_power_level *cp;
     struct net_buf *buf, *rsp = NULL;
 
     buf = bt_hci_cmd_alloc(K_MSEC(3000));
     if (!buf) {
-        mp_raise_msg(&mp_type_MemoryError, NULL);
+        return -ENOMEM;
     }
     cp = net_buf_add(buf, sizeof(*cp));
     cp->handle_type = BT_HCI_VS_LL_HANDLE_TYPE_ADV;
@@ -343,10 +346,19 @@ void common_hal_bleio_adapter_set_tx_power(bleio_adapter_obj_t *self, mp_int_t t
 
     int err = bt_hci_cmd_send_sync(BT_HCI_OP_VS_WRITE_TX_POWER_LEVEL, buf, &rsp);
     if (err) {
-        raise_zephyr_error(err);
+        return err;
     }
 
     net_buf_unref(rsp);
+    return 0;
+}
+
+void common_hal_bleio_adapter_set_tx_power(bleio_adapter_obj_t *self, mp_int_t tx_power) {
+    int err = _try_set_tx_power(tx_power);
+    if (err == -ENOMEM) {
+        mp_raise_msg(&mp_type_MemoryError, NULL);
+    }
+    raise_zephyr_error(err);
 }
 
 bleio_address_obj_t *common_hal_bleio_adapter_get_address(bleio_adapter_obj_t *self) {
@@ -454,7 +466,10 @@ void common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self,
             NULL);
     }
 
-    common_hal_bleio_adapter_set_tx_power(self, tx_power);
+    // Best-effort: a controller that does not implement Zephyr's vendor-specific
+    // Tx power command must still be able to advertise. tx_power defaults to 0,
+    // so reporting the rejection here would print on every start_advertising().
+    _try_set_tx_power(tx_power);
 
     raise_zephyr_error(bt_le_adv_start(&adv_params,
         adv_data,