Hi Marcel,
On Thu, Dec 10, 2009 at 2:03 PM, Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote:
> Hi Nick,
>
>> >> Right now Bluez always requests flushable ACL packets (but does not
>> >> set a flush timeout, so effectively they are non-flushable):
>> >>
>> >> However it is desirable to use an ACL flush timeout on A2DP packets so
>> >> that if the ACL packets block for some reason then the LM can flush
>> >> them to make room for newer packets.
>> >>
>> >> Is it reasonable for Bluez to use the 0x00 ACL packet boundary flag by
>> >> default (non-flushable packet), and let userspace request flushable
>> >> packets on A2DP L2CAP sockets with the socket option
>> >> L2CAP_LM_RELIABLE.
>> >
>> > the reliable option has a different meaning. It comes back from the old
>> > Bluetooth 1.1 qualification days where we had to tests on L2CAP that had
>> > to confirm that we can detect malformed packets and report them. These
>> > days it is just fine to drop them.
>>
>> Got it, how about introducing
>>
>> #define L2CAP_LM_FLUSHABLE 0x0040
>
> that l2cap_sock_setsockopt_old() sets this didn't give you a hint that
> we might wanna deprecate this socket options ;)
>
> I need to read up on the flushable stuff, but in the end it deserves its
> own socket option. Also an ioctl() to actually trigger Enhanced flush
> might be needed.
>
>> struct l2cap_pinfo {
>> ...
>> __u8 flushable;
>> }
>
> Sure. In the long run we need to turn this into a bitmask. We are just
> wasting memory here.
Attached is an updated patch, that checks the LMP features bitmask
before using the new non-flushable packet type.
I am still using L2CAP_LM_FLUSHABLE socket option in
l2cap_sock_setsockopt_old(), which I don't think you are happy with.
So how about a new option:
SOL_L2CAP, L2CAP_ACL_FLUSH
which has a default value of 0, and can be set to 1 to make the ACL
data sent by this L2CAP socket flushable.
In a later commit we would then add
SOL_ACL, ACL_FLUSH_TIMEOUT
That is used to set an automatic flush timeout for the ACL link on a
L2CAP socket. Note that SOL_ACL is new.
But maybe this is not what you had in mind, so I'm looking for your
advice before I implement this.
Nick
Attachment:
0001-Bluetooth-Use-non-flushable-pb-flag-by-default-for-A.patch
Description: Binary data
