Hello, All.
I plan to provide the kernel interface which is used by user space's
bluez to change LE connection parameters.
This is my first trial to implement new feature so I need help.
Would you please give me a comment ?
Are there any better ways ?
< Why this is required >
When the LE connection is in idle state (e.g. no traffic),
it is better to increase a connection interval for power saving reason.
Or it needs to reduce a connection interval for a fast response time.
And it may need to change a supervision timeout to detect link loss
faster or looser.
It is better to control these kind of things as per application's needs.
So I want to provide the interface to change LE connection parameters.
< Current state >
There is no interface to change LE connection parameters for already
connected link.
And LE connection parameter is only configured by remote device like below ways.
- remote device(slave) requests a change using l2cap connection
parameter request.
- remote device(master) sends HCI_OP_LE_CONN_UPDATE.
- If above configured parameters are loaded during adapter init.,
those are automatically applied during connection setup.
< How to implement >
When I roughly thought, below ways are possible.
1. Add new MGMT (e.g. MGMT_OP_UPDATE_CONN_PARAM)
In mgmt handler, based on the role and local / remote LE features,
do connection parameter update procedure as follows.
- If remote and local devices both support "HCI_LE_CONN_PARAM_REQ_PROC",
send HCI_OP_LE_CONN_UPDATE
- If either the remote or local or both do not support
"HCI_LE_CONN_PARAM_REQ_PROC",
- if local is master,
send HCI_OP_LE_CONN_UPDATE.
- if local is slave,
send L2CAP_CONN_PARAM_UPDATE_REQ via l2cap signal channel.
=> Main concern of this way is that it is possible to access l2cap from mgmt.
2. Add new MGMT and L2CAP socket option
- user space's bluez should know own role
- user space's bluez may know remote / local le features.
Or, based on the le features, net/core's l2cap may select a procedure.
3. Add new MGMT and send L2CAP command from user space's bluez
- user space's bluez should know own role
- user space's bluez may know remote / local le features.
Or, based on the le features, net/core's l2cap may select a procedure.
Thanks and Regards,
Seungyoun Ju
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