From 3621f78d43b0a9563d5ade68370434c532eea259 Mon Sep 17 00:00:00 2001 From: Luiz Augusto von Dentz Date: Wed, 2 Sep 2026 13:16:26 -0400 Subject: [PATCH] Bluetooth: hci_sync: Fix not setting CE length properly Both hci_le_set_def_rate_sync() and hci_le_conn_rate_request_sync() were leaving Min_CE_Length and Max_CE_Length set to 0x0000, but the connection event length recommended in requests by a Peripheral has a valid range of 0x0001 to 0x7CFF (Time = N * 125 us, Time Range: 0.125 ms to 3.999875 s), so 0x0000 cannot be used. Set both to the minimum valid value, which is safe since the Controller is not required to use these values: BLUETOOTH CORE SPECIFICATION Version 6.2 | Vol 4, Part E 7.8.157. LE Connection Rate Request command 7.8.158. LE Set Default Rate Parameters command The Min_CE_Length and Max_CE_Length parameters provide the Controller with the expected minimum and maximum length of the connection events. The Controller is not required to use these values. Fixes: 2f8784cfe8a9 ("Bluetooth: Add support for Shorter Connection Interval (SCI) feature") Signed-off-by: Luiz Augusto von Dentz --- net/bluetooth/hci_sync.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-) diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c index ffd7b37e7401..3ab5fa3dce96 100644 --- a/net/bluetooth/hci_sync.c +++ b/net/bluetooth/hci_sync.c @@ -4797,6 +4797,24 @@ static int hci_le_set_def_rate_sync(struct hci_dev *hdev) cp.cont_num = cpu_to_le16(0x0001); cp.supv_timeout = cpu_to_le16(0x000c); /* 120 ms */ + /* The connection event length recommended in requests by a Peripheral + * uses units of 125 us with a valid range of 0x0001 to 0x7CFF + * (0.125 ms to 3.999875 s), so 0x0000 cannot be used. Also note that + * the Controller is not required to use these values: + * + * BLUETOOTH CORE SPECIFICATION Version 6.2 | Vol 4, Part E + * 7.8.158. LE Set Default Rate Parameters command + * + * The Min_CE_Length and Max_CE_Length parameters provide the + * Controller with the expected minimum and maximum length of the + * connection events. The Controller is not required to use these + * values. + * + * So it is safe to just use the minimum. + */ + cp.min_ce_len = cpu_to_le16(0x0001); + cp.max_ce_len = cpu_to_le16(0x0001); + return __hci_cmd_sync_status(hdev, HCI_OP_LE_SET_DEF_RATE, sizeof(cp), &cp, HCI_CMD_TIMEOUT); } @@ -7467,8 +7485,24 @@ static int hci_le_conn_rate_request_sync(struct hci_dev *hdev, void *data) cp.max_latency = cpu_to_le16(params->max_latency); cp.cont_num = cpu_to_le16(params->cont_num); cp.supv_timeout = cpu_to_le16(params->rate_supv_timeout); - cp.min_ce_len = cpu_to_le16(0x0000); - cp.max_ce_len = cpu_to_le16(0x0000); + + /* The connection event length recommended in requests by a Peripheral + * uses units of 125 us with a valid range of 0x0001 to 0x7CFF + * (0.125 ms to 3.999875 s), so 0x0000 cannot be used. Also note that + * the Controller is not required to use these values: + * + * BLUETOOTH CORE SPECIFICATION Version 6.2 | Vol 4, Part E + * 7.8.157. LE Connection Rate Request command + * + * The Min_CE_Length and Max_CE_Length parameters provide the + * Controller with the expected minimum and maximum length of the + * connection events. The Controller is not required to use these + * values. + * + * So it is safe to just use the minimum. + */ + cp.min_ce_len = cpu_to_le16(0x0001); + cp.max_ce_len = cpu_to_le16(0x0001); hci_dev_unlock(hdev);