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Reply-To: Carey Sonsino <csonsino@gmail.com>
From:   Carey Sonsino <csonsino@gmail.com>
Subject: [PATCH 1/1] bluetooth: update default BLE connection params
To:     Marcel Holtmann <marcel@holtmann.org>,
        Johan Hedberg <johan.hedberg@gmail.com>
Cc:     Andreas Kemnade <andreas@kemnade.info>,
        Jamie Mccrae <Jamie.Mccrae@lairdconnect.com>,
        "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>
Message-ID: <705dbccb-58a9-7adc-8430-c16b395c27e5@gmail.com>
Date:   Wed, 4 Sep 2019 15:20:29 -0600
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Update the default BLE connection parameters.

Commit c49a8682fc5d298d44e8d911f4fa14690ea9485e introduced a bounds
check on connection interval update requests, but the default min/max
values were left at 24-40 (30-50ms) which caused problems for devices
that want to negotiate connection intervals outside of those bounds.

Setting the default min/max connection interval to the full allowable
range in the bluetooth specification restores the default Linux behavior
of allowing remote devices to negotiate their desired connection
interval, while still permitting the system administrator to later
narrow the range.

The default supervision timeout must also be modified to accommodate
the max connection interval increase.  The new default value meets the
requirements of the bluetooth specification and the conditions in
the hci_check_conn_params function.

The downside to modifying the default supervision timeout is that
it will take longer (about 10 seconds) to detect a link loss condition.

Fixes c49a8682fc5d: (validate BLE connection interval updates)

Signed-off-by: Carey Sonsino <csonsino@gmail.com>

---

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 04bc79359a17..895d17ec9291 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3181,10 +3181,10 @@ struct hci_dev *hci_alloc_dev(void)
  	hdev->le_adv_max_interval = 0x0800;
  	hdev->le_scan_interval = 0x0060;
  	hdev->le_scan_window = 0x0030;
-	hdev->le_conn_min_interval = 0x0018;
-	hdev->le_conn_max_interval = 0x0028;
+	hdev->le_conn_min_interval = 0x0006;
+	hdev->le_conn_max_interval = 0x0c80;
  	hdev->le_conn_latency = 0x0000;
-	hdev->le_supv_timeout = 0x002a;
+	hdev->le_supv_timeout = 0x03ea;
  	hdev->le_def_tx_len = 0x001b;
  	hdev->le_def_tx_time = 0x0148;
  	hdev->le_max_tx_len = 0x001b;