Re: Notify problem in gatt plugin

["Mathieu Ocaña" <mo@esd-dev.be>]

Hi Luiz,

Le 20/01/2015 10:30, Luiz Augusto von Dentz a écrit :
> Hi Mathieu,
>
> On Mon, Jan 19, 2015 at 6:20 PM, Mathieu Ocaña <mo@esd-dev.be> wrote:
>> Hello,
>>
>> I'm currently working on a plugin to implement a GATT peripheral. Based on
>> the plugins/gatt-example and the profiles/alert/server, I finally got
>> something which works: read, write, with dbus signaling.
>> But, notifications doesn't work...
>> All seems ok until the call to "g_attrib_send()".
>>
>>>> static void attio_connected_cb(GAttrib *attrib, gpointer user_data)
>>>> {
>>>>    [...]
>>>>    len = enc_notification(p_adapter->batterylevel_chr.level_hnd_value,
>>>>                      nd->value, nd->len, pdu, len);
>>>>    [...]
>>>>    ret = g_attrib_send(attrib, 0, pdu, len, destroy_notify_callback,
>>>> cb, NULL);
>>>>    return;
>>>> }
>>
>> The parameters passed to g_attrib_send seems valid, I have verified the pdu,
>> len and user_data, but I'm not sure to understand well all the fields of
>> "attrib" (struct _GAttrib). Moreover the return value is 0.
>>
>> Some extra details:
>> - the destroy_notify_callback is not called (maybe normal as the
>> notification is not succesfully sent).
>> - in g_attrib_send, the call to bt_att_send() return 0. After this point my
>> understanding of the source code became a little bit fuzzy.
> You might not be connected then so perhaps there is a bug in attio
> callback. Which version are you using?
I'm using the v5.27. I see no signs of disconnection in the debug 
messages, but I will explore this lead.
For now I use a Nordic dongle & software (master panel monitor) for my 
tests and the connection seems ok (even if the notificatons are not 
sent, the read/write operation are performed witout problem). But when I 
use gatttool I'm disconnected constantly after 5-15s, (in this case the 
debug log tells me it).
I have not yet tested with a BT LE-enabled smartphone, but if I'm also 
disconnected, maybe the two problems are related.

>>> It would be great if someone could suggest me a fix or a workaround.
>> I have also developped some extensions for the function gatt_service_add(),
>> such as the support of static value characteristic, and the descriptors for
>> presentation format, valid range and user description.
>>> Before submitting this patch, I want to know which is the patch policy for
>>> the bluez project? (validation test to perform, etc.).
> It is documented in Submitting patches section in the HACKING:
> https://git.kernel.org/cgit/bluetooth/bluez.git/tree/HACKING
Ok, I had totally forgotten this file. According to the coding 
standards, I've some modifications to do.
The answer is maybe obvious, but if I modify the behavior of the 
function gatt_service_add(), I should also patch the profiles and 
plugins which use it, accordingly?

Thank for your answer,

--
Mathieu OCAÑA