Hi All,
On Wed, Jun 16, 2010 at 5:15 PM, Nick Pelly <npelly@xxxxxxxxxx> wrote:
> On Wed, Jun 16, 2010 at 4:40 AM, Luiz Augusto von Dentz
> <luiz.dentz@xxxxxxxxx> wrote:
>> Hi,
>>
>> On Tue, Mar 9, 2010 at 11:45 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.
>>>>
>>>> Attached an updated patch for 2.6.32 kernel. We've been using this
>>>> patch successfully on production devices.
>>>
>>> can see anything wrong with that patch. However we need to use
>>> SOL_BLUETOOTH for it of course. So we need to come up with something to
>>> make this simple.
Nick are you going to take Marcel comments? Otherwise I could take
care about the patch as it seems that it might help in some
situations.
>>> An additional change I like to see is to use flags for booleans like
>>> flushable in the structures. Can you work on changing that.
>>>
>>> Also do we have decoding support for this in hcidump. It might be nice
>>> to include some really simple examples in the commit message.
At least wireshark which I use understands those packets.
>> I would like to play a little bit with this, so is there any missing updates?
>
> Nope, that is our most recent version.
Nick, do you know headset which could help to hear the real
difference? I was trying to use Sony DR-BT22 headset which has some
issues with A2DP but the solution did not help much.
Regards,
Andrei
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