BLE advertisement re-enabling after ble connection goes away

BLE advertisement re-enabling after ble connection goes away

[Yunhan Wang]

Hi, Luiz and Marcel

May I have a question on ble behavior on BLE re-advertisement?

According to Bluetooth spec Vol. 3 (the host volume), 9.2.4.2, "The
device shall remain in general discoverable mode until a connection is
established or the Host terminates the mode."

There is no description on re-enabling the advertising "after"
disconnection, so the responsibility for re-enabling the advertising
is bluez or kernel or application code? In other words, does kernel or
bluez or application would re-enable the ble advertisement after ble
disconnection happens?

Thanks
Best wishes
Yunhan.

Re: BLE advertisement re-enabling after ble connection goes away

[Yunhan Wang]

+Martin

Hi, Luiz and Marcel

When I take a look at the bluetooth code, it seems it is re-enabling
ble advertisement after ble connection goes away. Any idea?

https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2634
https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2712
https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1386
https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1734

Thanks
Best wishes
Yunhan
On Wed, Dec 5, 2018 at 6:54 PM Yunhan Wang <yunhanw@nestlabs.com> wrote:
>
> Hi, Luiz and Marcel
>
> May I have a question on ble behavior on BLE re-advertisement?
>
> According to Bluetooth spec Vol. 3 (the host volume), 9.2.4.2, "The
> device shall remain in general discoverable mode until a connection is
> established or the Host terminates the mode."
>
> There is no description on re-enabling the advertising "after"
> disconnection, so the responsibility for re-enabling the advertising
> is bluez or kernel or application code? In other words, does kernel or
> bluez or application would re-enable the ble advertisement after ble
> disconnection happens?
>
> Thanks
> Best wishes
> Yunhan.

Re: BLE advertisement re-enabling after ble connection goes away

[Yunhan Wang]

Hi, Luiz

From what you describes, it seems Bluez is taking the responsibility
to reenable the advertisement after the previous ble connection goes
away.

When I did local test, the ble peripheral is using bluez, I create
gatt server and ble advertisment using Bluez DBus API,  when remote
connection in central disconnects, I see kernel in Bluez do receive
HCI_EV_DISCONN_COMPLETE event, and trigger
hci_req_reenable_advertising.

Maybe you can share the code location where Bluez is reenabling the
advertisement after ble connection goes away?

Thanks
Best wishes
Yunhan

On Thu, Dec 13, 2018 at 2:30 PM Martin Turon <mturon@google.com> wrote:
>
> Hi Luiz,
>
> Is this behavior also expected on raw hci sockets?  Because my observation is that when working with raw hci over such sockets, auto-reenable does not occur.
>
>     #define BTPROTO_HCI                 1
>     #define HCI_CHANNEL_USER         1
>
>     struct sockaddr_hci shci;
>     shci.hci_family = AF_BLUETOOTH;
>     shci.hci_dev = s_ble_hci_device;
>     shci.hci_channel = HCI_CHANNEL_USER;
>
>     s = socket(PF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);
>     rc = bind(s, (struct sockaddr *)&shci, sizeof(shci));
>
> Also, which API allows the user to control the advertising instances you describe?  Are they automatically created by the kernel when HCI is sent to a raw socket to enable advertising?
>
> Thanks,
> Martin
>
> _____________________________
> Martin Turon  |  Google
>
>
>
> On Thu, Dec 13, 2018 at 1:49 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
>>
>> Hi Yunhan,
>>
>> The BlueZ API operates a bit different than HCI, it keeps re-enabling the advertisement if there is any instance active, but the user can stop this by removing its instance once a connection is made, this is considered more convenient than having the user to reprogram the advertisement on every disconnection.
>>
>> On Thu, 13 Dec 2018, 18:38 Yunhan Wang <yunhanw@nestlabs.com wrote:
>>>
>>> +Martin
>>>
>>> Hi, Luiz and Marcel
>>>
>>> When I take a look at the bluetooth code, it seems it is re-enabling
>>> ble advertisement after ble connection goes away. Any idea?
>>>
>>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2634
>>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2712
>>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1386
>>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1734
>>>
>>> Thanks
>>> Best wishes
>>> Yunhan
>>> On Wed, Dec 5, 2018 at 6:54 PM Yunhan Wang <yunhanw@nestlabs.com> wrote:
>>> >
>>> > Hi, Luiz and Marcel
>>> >
>>> > May I have a question on ble behavior on BLE re-advertisement?
>>> >
>>> > According to Bluetooth spec Vol. 3 (the host volume), 9.2.4.2, "The
>>> > device shall remain in general discoverable mode until a connection is
>>> > established or the Host terminates the mode."
>>> >
>>> > There is no description on re-enabling the advertising "after"
>>> > disconnection, so the responsibility for re-enabling the advertising
>>> > is bluez or kernel or application code? In other words, does kernel or
>>> > bluez or application would re-enable the ble advertisement after ble
>>> > disconnection happens?
>>> >
>>> > Thanks
>>> > Best wishes
>>> > Yunhan.

Re: BLE advertisement re-enabling after ble connection goes away

[Yunhan Wang]

Hi, Luiz

Rephrasing a little bit..

From what you describes, it seems Bluez is taking the responsibility
to reenable the advertisement in peripheral side after the previous
ble connection goes
away.

When I did local test, the ble peripheral is using bluez, I create
gatt server and ble advertisment using Bluez DBus API,  when remote
connection in central disconnects, I see kernel in Bluez in peripheral
side do receive
HCI_EV_DISCONN_COMPLETE event, and trigger
hci_req_reenable_advertising.

Maybe you can share the code location where Bluez is reenabling the
advertisement after ble connection goes away?

Thanks
Best wishes
On Thu, Dec 13, 2018 at 3:10 PM Yunhan Wang <yunhanw@nestlabs.com> wrote:
>
> Hi, Luiz
>
> From what you describes, it seems Bluez is taking the responsibility
> to reenable the advertisement after the previous ble connection goes
> away.
>
> When I did local test, the ble peripheral is using bluez, I create
> gatt server and ble advertisment using Bluez DBus API,  when remote
> connection in central disconnects, I see kernel in Bluez do receive
> HCI_EV_DISCONN_COMPLETE event, and trigger
> hci_req_reenable_advertising.
>
> Maybe you can share the code location where Bluez is reenabling the
> advertisement after ble connection goes away?
>
> Thanks
> Best wishes
> Yunhan
>
> On Thu, Dec 13, 2018 at 2:30 PM Martin Turon <mturon@google.com> wrote:
> >
> > Hi Luiz,
> >
> > Is this behavior also expected on raw hci sockets?  Because my observation is that when working with raw hci over such sockets, auto-reenable does not occur.
> >
> >     #define BTPROTO_HCI                 1
> >     #define HCI_CHANNEL_USER         1
> >
> >     struct sockaddr_hci shci;
> >     shci.hci_family = AF_BLUETOOTH;
> >     shci.hci_dev = s_ble_hci_device;
> >     shci.hci_channel = HCI_CHANNEL_USER;
> >
> >     s = socket(PF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);
> >     rc = bind(s, (struct sockaddr *)&shci, sizeof(shci));
> >
> > Also, which API allows the user to control the advertising instances you describe?  Are they automatically created by the kernel when HCI is sent to a raw socket to enable advertising?
> >
> > Thanks,
> > Martin
> >
> > _____________________________
> > Martin Turon  |  Google
> >
> >
> >
> > On Thu, Dec 13, 2018 at 1:49 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
> >>
> >> Hi Yunhan,
> >>
> >> The BlueZ API operates a bit different than HCI, it keeps re-enabling the advertisement if there is any instance active, but the user can stop this by removing its instance once a connection is made, this is considered more convenient than having the user to reprogram the advertisement on every disconnection.
> >>
> >> On Thu, 13 Dec 2018, 18:38 Yunhan Wang <yunhanw@nestlabs.com wrote:
> >>>
> >>> +Martin
> >>>
> >>> Hi, Luiz and Marcel
> >>>
> >>> When I take a look at the bluetooth code, it seems it is re-enabling
> >>> ble advertisement after ble connection goes away. Any idea?
> >>>
> >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2634
> >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2712
> >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1386
> >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1734
> >>>
> >>> Thanks
> >>> Best wishes
> >>> Yunhan
> >>> On Wed, Dec 5, 2018 at 6:54 PM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> >>> >
> >>> > Hi, Luiz and Marcel
> >>> >
> >>> > May I have a question on ble behavior on BLE re-advertisement?
> >>> >
> >>> > According to Bluetooth spec Vol. 3 (the host volume), 9.2.4.2, "The
> >>> > device shall remain in general discoverable mode until a connection is
> >>> > established or the Host terminates the mode."
> >>> >
> >>> > There is no description on re-enabling the advertising "after"
> >>> > disconnection, so the responsibility for re-enabling the advertising
> >>> > is bluez or kernel or application code? In other words, does kernel or
> >>> > bluez or application would re-enable the ble advertisement after ble
> >>> > disconnection happens?
> >>> >
> >>> > Thanks
> >>> > Best wishes
> >>> > Yunhan.

Re: BLE advertisement re-enabling after ble connection goes away

[Luiz Augusto von Dentz]

Hi Yunhan,

You already answered your question, it is reenabled by
hci_req_reenable_advertising


On Fri, Dec 14, 2018 at 1:13 AM Yunhan Wang <yunhanw@nestlabs.com> wrote:
>
> Hi, Luiz
>
> Rephrasing a little bit..
>
> From what you describes, it seems Bluez is taking the responsibility
> to reenable the advertisement in peripheral side after the previous
> ble connection goes
> away.
>
> When I did local test, the ble peripheral is using bluez, I create
> gatt server and ble advertisment using Bluez DBus API,  when remote
> connection in central disconnects, I see kernel in Bluez in peripheral
> side do receive
> HCI_EV_DISCONN_COMPLETE event, and trigger
> hci_req_reenable_advertising.
>
> Maybe you can share the code location where Bluez is reenabling the
> advertisement after ble connection goes away?
>
> Thanks
> Best wishes
> On Thu, Dec 13, 2018 at 3:10 PM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> >
> > Hi, Luiz
> >
> > From what you describes, it seems Bluez is taking the responsibility
> > to reenable the advertisement after the previous ble connection goes
> > away.
> >
> > When I did local test, the ble peripheral is using bluez, I create
> > gatt server and ble advertisment using Bluez DBus API,  when remote
> > connection in central disconnects, I see kernel in Bluez do receive
> > HCI_EV_DISCONN_COMPLETE event, and trigger
> > hci_req_reenable_advertising.
> >
> > Maybe you can share the code location where Bluez is reenabling the
> > advertisement after ble connection goes away?
> >
> > Thanks
> > Best wishes
> > Yunhan
> >
> > On Thu, Dec 13, 2018 at 2:30 PM Martin Turon <mturon@google.com> wrote:
> > >
> > > Hi Luiz,
> > >
> > > Is this behavior also expected on raw hci sockets?  Because my observation is that when working with raw hci over such sockets, auto-reenable does not occur.
> > >
> > >     #define BTPROTO_HCI                 1
> > >     #define HCI_CHANNEL_USER         1
> > >
> > >     struct sockaddr_hci shci;
> > >     shci.hci_family = AF_BLUETOOTH;
> > >     shci.hci_dev = s_ble_hci_device;
> > >     shci.hci_channel = HCI_CHANNEL_USER;
> > >
> > >     s = socket(PF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);
> > >     rc = bind(s, (struct sockaddr *)&shci, sizeof(shci));

Raw socket commands might actually work but here you are using it with
a user channel which afaik disables the stack processing.

> > > Also, which API allows the user to control the advertising instances you describe?  Are they automatically created by the kernel when HCI is sent to a raw socket to enable advertising?

Nope you need to use the management interface to use the advertising
instances, or better yet use the D-Bus API:

https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/advertising-api.txt

> > > Thanks,
> > > Martin
> > >
> > > _____________________________
> > > Martin Turon  |  Google
> > >
> > >
> > >
> > > On Thu, Dec 13, 2018 at 1:49 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
> > >>
> > >> Hi Yunhan,
> > >>
> > >> The BlueZ API operates a bit different than HCI, it keeps re-enabling the advertisement if there is any instance active, but the user can stop this by removing its instance once a connection is made, this is considered more convenient than having the user to reprogram the advertisement on every disconnection.
> > >>
> > >> On Thu, 13 Dec 2018, 18:38 Yunhan Wang <yunhanw@nestlabs.com wrote:
> > >>>
> > >>> +Martin
> > >>>
> > >>> Hi, Luiz and Marcel
> > >>>
> > >>> When I take a look at the bluetooth code, it seems it is re-enabling
> > >>> ble advertisement after ble connection goes away. Any idea?
> > >>>
> > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2634
> > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2712
> > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1386
> > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1734
> > >>>
> > >>> Thanks
> > >>> Best wishes
> > >>> Yunhan
> > >>> On Wed, Dec 5, 2018 at 6:54 PM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> > >>> >
> > >>> > Hi, Luiz and Marcel
> > >>> >
> > >>> > May I have a question on ble behavior on BLE re-advertisement?
> > >>> >
> > >>> > According to Bluetooth spec Vol. 3 (the host volume), 9.2.4.2, "The
> > >>> > device shall remain in general discoverable mode until a connection is
> > >>> > established or the Host terminates the mode."
> > >>> >
> > >>> > There is no description on re-enabling the advertising "after"
> > >>> > disconnection, so the responsibility for re-enabling the advertising
> > >>> > is bluez or kernel or application code? In other words, does kernel or
> > >>> > bluez or application would re-enable the ble advertisement after ble
> > >>> > disconnection happens?
> > >>> >
> > >>> > Thanks
> > >>> > Best wishes
> > >>> > Yunhan.



-- 
Luiz Augusto von Dentz

Re: BLE advertisement re-enabling after ble connection goes away

[Yunhan Wang]

Hi, Luiz

Thanks for your reply. A little bit confused here.

There is no code in bluez that directly re-enable advertisement, if
there is, could you show the code location in bluez?

Bluetooth in kernel is responsible for re-enabling advertisement? The
responsibility for re-enabling the advertising is kernel instead of
bluez and user application code.

Thanks
Best wishes
Yunhan



On Thu, Dec 13, 2018 at 5:21 PM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Yunhan,
>
> You already answered your question, it is reenabled by
> hci_req_reenable_advertising
>
>
> On Fri, Dec 14, 2018 at 1:13 AM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> >
> > Hi, Luiz
> >
> > Rephrasing a little bit..
> >
> > From what you describes, it seems Bluez is taking the responsibility
> > to reenable the advertisement in peripheral side after the previous
> > ble connection goes
> > away.
> >
> > When I did local test, the ble peripheral is using bluez, I create
> > gatt server and ble advertisment using Bluez DBus API,  when remote
> > connection in central disconnects, I see kernel in Bluez in peripheral
> > side do receive
> > HCI_EV_DISCONN_COMPLETE event, and trigger
> > hci_req_reenable_advertising.
> >
> > Maybe you can share the code location where Bluez is reenabling the
> > advertisement after ble connection goes away?
> >
> > Thanks
> > Best wishes
> > On Thu, Dec 13, 2018 at 3:10 PM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> > >
> > > Hi, Luiz
> > >
> > > From what you describes, it seems Bluez is taking the responsibility
> > > to reenable the advertisement after the previous ble connection goes
> > > away.
> > >
> > > When I did local test, the ble peripheral is using bluez, I create
> > > gatt server and ble advertisment using Bluez DBus API,  when remote
> > > connection in central disconnects, I see kernel in Bluez do receive
> > > HCI_EV_DISCONN_COMPLETE event, and trigger
> > > hci_req_reenable_advertising.
> > >
> > > Maybe you can share the code location where Bluez is reenabling the
> > > advertisement after ble connection goes away?
> > >
> > > Thanks
> > > Best wishes
> > > Yunhan
> > >
> > > On Thu, Dec 13, 2018 at 2:30 PM Martin Turon <mturon@google.com> wrote:
> > > >
> > > > Hi Luiz,
> > > >
> > > > Is this behavior also expected on raw hci sockets?  Because my observation is that when working with raw hci over such sockets, auto-reenable does not occur.
> > > >
> > > >     #define BTPROTO_HCI                 1
> > > >     #define HCI_CHANNEL_USER         1
> > > >
> > > >     struct sockaddr_hci shci;
> > > >     shci.hci_family = AF_BLUETOOTH;
> > > >     shci.hci_dev = s_ble_hci_device;
> > > >     shci.hci_channel = HCI_CHANNEL_USER;
> > > >
> > > >     s = socket(PF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);
> > > >     rc = bind(s, (struct sockaddr *)&shci, sizeof(shci));
>
> Raw socket commands might actually work but here you are using it with
> a user channel which afaik disables the stack processing.
>
> > > > Also, which API allows the user to control the advertising instances you describe?  Are they automatically created by the kernel when HCI is sent to a raw socket to enable advertising?
>
> Nope you need to use the management interface to use the advertising
> instances, or better yet use the D-Bus API:
>
> https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/advertising-api.txt
>
> > > > Thanks,
> > > > Martin
> > > >
> > > > _____________________________
> > > > Martin Turon  |  Google
> > > >
> > > >
> > > >
> > > > On Thu, Dec 13, 2018 at 1:49 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
> > > >>
> > > >> Hi Yunhan,
> > > >>
> > > >> The BlueZ API operates a bit different than HCI, it keeps re-enabling the advertisement if there is any instance active, but the user can stop this by removing its instance once a connection is made, this is considered more convenient than having the user to reprogram the advertisement on every disconnection.
> > > >>
> > > >> On Thu, 13 Dec 2018, 18:38 Yunhan Wang <yunhanw@nestlabs.com wrote:
> > > >>>
> > > >>> +Martin
> > > >>>
> > > >>> Hi, Luiz and Marcel
> > > >>>
> > > >>> When I take a look at the bluetooth code, it seems it is re-enabling
> > > >>> ble advertisement after ble connection goes away. Any idea?
> > > >>>
> > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2634
> > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2712
> > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1386
> > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1734
> > > >>>
> > > >>> Thanks
> > > >>> Best wishes
> > > >>> Yunhan
> > > >>> On Wed, Dec 5, 2018 at 6:54 PM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> > > >>> >
> > > >>> > Hi, Luiz and Marcel
> > > >>> >
> > > >>> > May I have a question on ble behavior on BLE re-advertisement?
> > > >>> >
> > > >>> > According to Bluetooth spec Vol. 3 (the host volume), 9.2.4.2, "The
> > > >>> > device shall remain in general discoverable mode until a connection is
> > > >>> > established or the Host terminates the mode."
> > > >>> >
> > > >>> > There is no description on re-enabling the advertising "after"
> > > >>> > disconnection, so the responsibility for re-enabling the advertising
> > > >>> > is bluez or kernel or application code? In other words, does kernel or
> > > >>> > bluez or application would re-enable the ble advertisement after ble
> > > >>> > disconnection happens?
> > > >>> >
> > > >>> > Thanks
> > > >>> > Best wishes
> > > >>> > Yunhan.
>
>
>
> --
> Luiz Augusto von Dentz

Re: BLE advertisement re-enabling after ble connection goes away

[Luiz Augusto von Dentz]

Hi Yunhan,

On Fri, Dec 14, 2018 at 4:06 AM Yunhan Wang <yunhanw@nestlabs.com> wrote:
>
> Hi, Luiz
>
> Thanks for your reply. A little bit confused here.
>
> There is no code in bluez that directly re-enable advertisement, if
> there is, could you show the code location in bluez?

Isn't that what the following code does:

https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1386

> Bluetooth in kernel is responsible for re-enabling advertisement? The
> responsibility for re-enabling the advertising is kernel instead of
> bluez and user application code.

Yes it is the kernel which re-enables it and it has been doing this
for a long while so I wonder why all of the a sudden we are discussing
about it. Is there a bug related to it?

> Thanks
> Best wishes
> Yunhan
>
>
>
> On Thu, Dec 13, 2018 at 5:21 PM Luiz Augusto von Dentz
> <luiz.dentz@gmail.com> wrote:
> >
> > Hi Yunhan,
> >
> > You already answered your question, it is reenabled by
> > hci_req_reenable_advertising
> >
> >
> > On Fri, Dec 14, 2018 at 1:13 AM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> > >
> > > Hi, Luiz
> > >
> > > Rephrasing a little bit..
> > >
> > > From what you describes, it seems Bluez is taking the responsibility
> > > to reenable the advertisement in peripheral side after the previous
> > > ble connection goes
> > > away.
> > >
> > > When I did local test, the ble peripheral is using bluez, I create
> > > gatt server and ble advertisment using Bluez DBus API,  when remote
> > > connection in central disconnects, I see kernel in Bluez in peripheral
> > > side do receive
> > > HCI_EV_DISCONN_COMPLETE event, and trigger
> > > hci_req_reenable_advertising.
> > >
> > > Maybe you can share the code location where Bluez is reenabling the
> > > advertisement after ble connection goes away?
> > >
> > > Thanks
> > > Best wishes
> > > On Thu, Dec 13, 2018 at 3:10 PM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> > > >
> > > > Hi, Luiz
> > > >
> > > > From what you describes, it seems Bluez is taking the responsibility
> > > > to reenable the advertisement after the previous ble connection goes
> > > > away.
> > > >
> > > > When I did local test, the ble peripheral is using bluez, I create
> > > > gatt server and ble advertisment using Bluez DBus API,  when remote
> > > > connection in central disconnects, I see kernel in Bluez do receive
> > > > HCI_EV_DISCONN_COMPLETE event, and trigger
> > > > hci_req_reenable_advertising.
> > > >
> > > > Maybe you can share the code location where Bluez is reenabling the
> > > > advertisement after ble connection goes away?
> > > >
> > > > Thanks
> > > > Best wishes
> > > > Yunhan
> > > >
> > > > On Thu, Dec 13, 2018 at 2:30 PM Martin Turon <mturon@google.com> wrote:
> > > > >
> > > > > Hi Luiz,
> > > > >
> > > > > Is this behavior also expected on raw hci sockets?  Because my observation is that when working with raw hci over such sockets, auto-reenable does not occur.
> > > > >
> > > > >     #define BTPROTO_HCI                 1
> > > > >     #define HCI_CHANNEL_USER         1
> > > > >
> > > > >     struct sockaddr_hci shci;
> > > > >     shci.hci_family = AF_BLUETOOTH;
> > > > >     shci.hci_dev = s_ble_hci_device;
> > > > >     shci.hci_channel = HCI_CHANNEL_USER;
> > > > >
> > > > >     s = socket(PF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);
> > > > >     rc = bind(s, (struct sockaddr *)&shci, sizeof(shci));
> >
> > Raw socket commands might actually work but here you are using it with
> > a user channel which afaik disables the stack processing.
> >
> > > > > Also, which API allows the user to control the advertising instances you describe?  Are they automatically created by the kernel when HCI is sent to a raw socket to enable advertising?
> >
> > Nope you need to use the management interface to use the advertising
> > instances, or better yet use the D-Bus API:
> >
> > https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/advertising-api.txt
> >
> > > > > Thanks,
> > > > > Martin
> > > > >
> > > > > _____________________________
> > > > > Martin Turon  |  Google
> > > > >
> > > > >
> > > > >
> > > > > On Thu, Dec 13, 2018 at 1:49 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
> > > > >>
> > > > >> Hi Yunhan,
> > > > >>
> > > > >> The BlueZ API operates a bit different than HCI, it keeps re-enabling the advertisement if there is any instance active, but the user can stop this by removing its instance once a connection is made, this is considered more convenient than having the user to reprogram the advertisement on every disconnection.
> > > > >>
> > > > >> On Thu, 13 Dec 2018, 18:38 Yunhan Wang <yunhanw@nestlabs.com wrote:
> > > > >>>
> > > > >>> +Martin
> > > > >>>
> > > > >>> Hi, Luiz and Marcel
> > > > >>>
> > > > >>> When I take a look at the bluetooth code, it seems it is re-enabling
> > > > >>> ble advertisement after ble connection goes away. Any idea?
> > > > >>>
> > > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2634
> > > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2712
> > > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1386
> > > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1734
> > > > >>>
> > > > >>> Thanks
> > > > >>> Best wishes
> > > > >>> Yunhan
> > > > >>> On Wed, Dec 5, 2018 at 6:54 PM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> > > > >>> >
> > > > >>> > Hi, Luiz and Marcel
> > > > >>> >
> > > > >>> > May I have a question on ble behavior on BLE re-advertisement?
> > > > >>> >
> > > > >>> > According to Bluetooth spec Vol. 3 (the host volume), 9.2.4.2, "The
> > > > >>> > device shall remain in general discoverable mode until a connection is
> > > > >>> > established or the Host terminates the mode."
> > > > >>> >
> > > > >>> > There is no description on re-enabling the advertising "after"
> > > > >>> > disconnection, so the responsibility for re-enabling the advertising
> > > > >>> > is bluez or kernel or application code? In other words, does kernel or
> > > > >>> > bluez or application would re-enable the ble advertisement after ble
> > > > >>> > disconnection happens?
> > > > >>> >
> > > > >>> > Thanks
> > > > >>> > Best wishes
> > > > >>> > Yunhan.
> >
> >
> >
> > --
> > Luiz Augusto von Dentz



-- 
Luiz Augusto von Dentz

Re: BLE advertisement re-enabling after ble connection goes away

[Yunhan Wang]

Hi, Luiz

Thanks for the clarification.

On Thu, Dec 13, 2018 at 6:32 PM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Yunhan,
>
> On Fri, Dec 14, 2018 at 4:06 AM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> >
> > Hi, Luiz
> >
> > Thanks for your reply. A little bit confused here.
> >
> > There is no code in bluez that directly re-enable advertisement, if
> > there is, could you show the code location in bluez?
>
> Isn't that what the following code does:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1386
>

I think this link is bluetooth code in kernel, and it is not bluez
code. Now I understand you think this bluetooth code is part of
bluez..

> > Bluetooth in kernel is responsible for re-enabling advertisement? The
> > responsibility for re-enabling the advertising is kernel instead of
> > bluez and user application code.
>
> Yes it is the kernel which re-enables it and it has been doing this
> for a long while so I wonder why all of the a sudden we are discussing
> about it. Is there a bug related to it?
>
I am seeing chrome os bluetooth kernel doesn't re-enable
advertisement, so I wanna figure out if bluetooth in kernel or bluez
user space or user application needs take this responsibility to
re-enable the advertisement. Clearly you mention bluetooth kernel
needs to re-enable the advertisement, I would further figure out the
root cause in chrome os kernel...

Thanks
Best wishes
Yunhan
> > Thanks
> > Best wishes
> > Yunhan
> >
> >
> >
> > On Thu, Dec 13, 2018 at 5:21 PM Luiz Augusto von Dentz
> > <luiz.dentz@gmail.com> wrote:
> > >
> > > Hi Yunhan,
> > >
> > > You already answered your question, it is reenabled by
> > > hci_req_reenable_advertising
> > >
> > >
> > > On Fri, Dec 14, 2018 at 1:13 AM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> > > >
> > > > Hi, Luiz
> > > >
> > > > Rephrasing a little bit..
> > > >
> > > > From what you describes, it seems Bluez is taking the responsibility
> > > > to reenable the advertisement in peripheral side after the previous
> > > > ble connection goes
> > > > away.
> > > >
> > > > When I did local test, the ble peripheral is using bluez, I create
> > > > gatt server and ble advertisment using Bluez DBus API,  when remote
> > > > connection in central disconnects, I see kernel in Bluez in peripheral
> > > > side do receive
> > > > HCI_EV_DISCONN_COMPLETE event, and trigger
> > > > hci_req_reenable_advertising.
> > > >
> > > > Maybe you can share the code location where Bluez is reenabling the
> > > > advertisement after ble connection goes away?
> > > >
> > > > Thanks
> > > > Best wishes
> > > > On Thu, Dec 13, 2018 at 3:10 PM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> > > > >
> > > > > Hi, Luiz
> > > > >
> > > > > From what you describes, it seems Bluez is taking the responsibility
> > > > > to reenable the advertisement after the previous ble connection goes
> > > > > away.
> > > > >
> > > > > When I did local test, the ble peripheral is using bluez, I create
> > > > > gatt server and ble advertisment using Bluez DBus API,  when remote
> > > > > connection in central disconnects, I see kernel in Bluez do receive
> > > > > HCI_EV_DISCONN_COMPLETE event, and trigger
> > > > > hci_req_reenable_advertising.
> > > > >
> > > > > Maybe you can share the code location where Bluez is reenabling the
> > > > > advertisement after ble connection goes away?
> > > > >
> > > > > Thanks
> > > > > Best wishes
> > > > > Yunhan
> > > > >
> > > > > On Thu, Dec 13, 2018 at 2:30 PM Martin Turon <mturon@google.com> wrote:
> > > > > >
> > > > > > Hi Luiz,
> > > > > >
> > > > > > Is this behavior also expected on raw hci sockets?  Because my observation is that when working with raw hci over such sockets, auto-reenable does not occur.
> > > > > >
> > > > > >     #define BTPROTO_HCI                 1
> > > > > >     #define HCI_CHANNEL_USER         1
> > > > > >
> > > > > >     struct sockaddr_hci shci;
> > > > > >     shci.hci_family = AF_BLUETOOTH;
> > > > > >     shci.hci_dev = s_ble_hci_device;
> > > > > >     shci.hci_channel = HCI_CHANNEL_USER;
> > > > > >
> > > > > >     s = socket(PF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);
> > > > > >     rc = bind(s, (struct sockaddr *)&shci, sizeof(shci));
> > >
> > > Raw socket commands might actually work but here you are using it with
> > > a user channel which afaik disables the stack processing.
> > >
> > > > > > Also, which API allows the user to control the advertising instances you describe?  Are they automatically created by the kernel when HCI is sent to a raw socket to enable advertising?
> > >
> > > Nope you need to use the management interface to use the advertising
> > > instances, or better yet use the D-Bus API:
> > >
> > > https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/advertising-api.txt
> > >
> > > > > > Thanks,
> > > > > > Martin
> > > > > >
> > > > > > _____________________________
> > > > > > Martin Turon  |  Google
> > > > > >
> > > > > >
> > > > > >
> > > > > > On Thu, Dec 13, 2018 at 1:49 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
> > > > > >>
> > > > > >> Hi Yunhan,
> > > > > >>
> > > > > >> The BlueZ API operates a bit different than HCI, it keeps re-enabling the advertisement if there is any instance active, but the user can stop this by removing its instance once a connection is made, this is considered more convenient than having the user to reprogram the advertisement on every disconnection.
> > > > > >>
> > > > > >> On Thu, 13 Dec 2018, 18:38 Yunhan Wang <yunhanw@nestlabs.com wrote:
> > > > > >>>
> > > > > >>> +Martin
> > > > > >>>
> > > > > >>> Hi, Luiz and Marcel
> > > > > >>>
> > > > > >>> When I take a look at the bluetooth code, it seems it is re-enabling
> > > > > >>> ble advertisement after ble connection goes away. Any idea?
> > > > > >>>
> > > > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2634
> > > > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_event.c#n2712
> > > > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1386
> > > > > >>> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/tree/net/bluetooth/hci_request.c#n1734
> > > > > >>>
> > > > > >>> Thanks
> > > > > >>> Best wishes
> > > > > >>> Yunhan
> > > > > >>> On Wed, Dec 5, 2018 at 6:54 PM Yunhan Wang <yunhanw@nestlabs.com> wrote:
> > > > > >>> >
> > > > > >>> > Hi, Luiz and Marcel
> > > > > >>> >
> > > > > >>> > May I have a question on ble behavior on BLE re-advertisement?
> > > > > >>> >
> > > > > >>> > According to Bluetooth spec Vol. 3 (the host volume), 9.2.4.2, "The
> > > > > >>> > device shall remain in general discoverable mode until a connection is
> > > > > >>> > established or the Host terminates the mode."
> > > > > >>> >
> > > > > >>> > There is no description on re-enabling the advertising "after"
> > > > > >>> > disconnection, so the responsibility for re-enabling the advertising
> > > > > >>> > is bluez or kernel or application code? In other words, does kernel or
> > > > > >>> > bluez or application would re-enable the ble advertisement after ble
> > > > > >>> > disconnection happens?
> > > > > >>> >
> > > > > >>> > Thanks
> > > > > >>> > Best wishes
> > > > > >>> > Yunhan.
> > >
> > >
> > >
> > > --
> > > Luiz Augusto von Dentz
>
>
>
> --
> Luiz Augusto von Dentz