[PATCH 1/1] bluetooth: update default BLE connection params

[PATCH 1/1] bluetooth: update default BLE connection params

[Carey Sonsino]

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;

Re: [PATCH 1/1] bluetooth: update default BLE connection params

[Marcel Holtmann]

Hi Carey,

> 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)

I decided to revert c49a8682fc5d and we need an overall better solution for handling connection parameters.

Regards

Marcel

Re: [PATCH 1/1] bluetooth: update default BLE connection params

[Andreas Kemnade]

Hi,

On Thu, 5 Sep 2019 17:34:03 +0200
Marcel Holtmann <marcel@holtmann.org> wrote:

> Hi Carey,
> 
> > 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)  
> 
> I decided to revert c49a8682fc5d and we need an overall better solution for handling connection parameters.
> 
is this revert also going towards stable/longterm? I do not see it in
stable-queue yet. 

Regards,
Andreas