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* [PATCH v2] Bluetooth: hci_sync: Fix not setting CE length properly
@ 2026-09-02 17:16 Luiz Augusto von Dentz
  2026-09-02 19:29 ` [v2] " bluez.test.bot
  2026-09-03 20:00 ` [PATCH v2] " patchwork-bot+bluetooth
  0 siblings, 2 replies; 3+ messages in thread
From: Luiz Augusto von Dentz @ 2026-09-02 17:16 UTC (permalink / raw)
  To: linux-bluetooth

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

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 <luiz.von.dentz@intel.com>
---
 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 24eeb76f7207..5376ade2cdc1 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);
 }
@@ -7457,8 +7475,24 @@ 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);
 
-- 
2.54.0


^ permalink raw reply related	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-09-03 20:01 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2026-09-02 17:16 [PATCH v2] Bluetooth: hci_sync: Fix not setting CE length properly Luiz Augusto von Dentz
2026-09-02 19:29 ` [v2] " bluez.test.bot
2026-09-03 20:00 ` [PATCH v2] " patchwork-bot+bluetooth

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