Hi everyone,
I would like to discuss a use-case that I encountered on my project, and
for which I cannot find a right way to do it with mgmt API.
I have a controller, the 88W8887 that I need to set in 'wakeup host' mode.
I put my host in suspend-to-mem, and the controller toggles a GPIO to wake
it up under certain circumstances, including a Low Energy connection.
To do that, I need to :
- configure precisely my advertising intervals, to be in low duty
cycle advertising, with a long interval between advertisements
- configure the filter policy, to only process connection
requests from whitelisted devices ( we want only whitelisted
devices to be able to wakeup our system ).
I previously did that with the HCI lib in my C program, and submitted a
patch to the hci lib, to add the le_set_advertising_parameters to the lib.
I used the following HCI commands :
- LE clear whitelist ( OCF 0x0010 )
- LE Add device to whitelist ( OCF 0x0011 )
- LE Set advertising parameters ( OCF 0x0006 )
- LE Set advertise enable ( OCF 0x000A )
It turns out this is not the right approach, Johan Hedberg explained to me
on IRC that the hci lib was not intended to be used by external programs.
Therefore, I'm looking for a way to do it using the mgmt API, but I can't
find a way to :
- Manipulate the whitelist
- Configure advertising intervals
- Configure the filter policy
If I missed something in the mgmt API that would allow me to do that, please
point it to me. If these are some missing features, I am willing to spend some
time working on it.
Thanks in advance,
Maxime Chevallier
Hi Maxime,
>>>>> I would like to discuss a use-case that I encountered on my project, and
>>>>> for which I cannot find a right way to do it with mgmt API.
>>>>>
>>>>> I have a controller, the 88W8887 that I need to set in 'wakeup host' mode.
>>>>>
>>>>> I put my host in suspend-to-mem, and the controller toggles a GPIO to wake
>>>>> it up under certain circumstances, including a Low Energy connection.
>>>>>
>>>>> To do that, I need to :
>>>>> - configure precisely my advertising intervals, to be in low duty
>>>>> cycle advertising, with a long interval between advertisements
>>>>> - configure the filter policy, to only process connection
>>>>> requests from whitelisted devices ( we want only whitelisted
>>>>> devices to be able to wakeup our system ).
>>>>>
>>>>> I previously did that with the HCI lib in my C program, and submitted a
>>>>> patch to the hci lib, to add the le_set_advertising_parameters to the lib.
>>>>>
>>>>> I used the following HCI commands :
>>>>> - LE clear whitelist ( OCF 0x0010 )
>>>>> - LE Add device to whitelist ( OCF 0x0011 )
>>>>> - LE Set advertising parameters ( OCF 0x0006 )
>>>>> - LE Set advertise enable ( OCF 0x000A )
>>>>>
>>>>> It turns out this is not the right approach, Johan Hedberg explained to me
>>>>> on IRC that the hci lib was not intended to be used by external programs.
>>>>>
>>>>> Therefore, I'm looking for a way to do it using the mgmt API, but I can't
>>>>> find a way to :
>>>>> - Manipulate the whitelist
>>>>> - Configure advertising intervals
>>>>> - Configure the filter policy
>>>>>
>>>>> If I missed something in the mgmt API that would allow me to do that, please
>>>>> point it to me. If these are some missing features, I am willing to spend some
>>>>> time working on it.
>>>>
>>>> it sounds to me that Add Device with type 0x01 is actually what we really wanted to support here. We currently use that for directed connections. So maybe we introduce a type 0x03 which has different meaning on LE compared to 0x01, but for BR/EDR it would actually result in 0x03 defining the incoming connections type for both bearers. On the other hand, is anybody actually using type 0x01 for LE?
>>>>
>>>> So only tricky part is that when using the whitelist for limiting LL_CONNECT_REQ processing is that we can then not background scan with a whitelist. Since that list might be different. So this is something we need to figure out on what chips actually do here. Or we have to create some combined whitelist and accept false positives that we handle in the host then.
>>>
>>> I get what you mean for Add Device with Action 0x03, that would fit my needs.
>>>
>>> I think however that there needs to be a way to specify if we take the
>>> whitelist into account while scanning of advertising in connectable mode.
>>
>> that is clearly not a parameter that we are exposing we are mgmt. The scanning policy is an internal detail.
>>
>>> I fail to see when we should take the whitelist into account in the current
>>> workflows proposed by the API. I get that blocking with Block Device
>>> establishes a blacklist, that Add Device could be used to "whitelist" a
>>> device, but I think there needs to be a way to set a mode where only
>>> whitelisted devices are taken into account for discovery and connection.
>>>
>>> Sorry if this is unclear, I don't have a full understanding of all the
>>> mecanisms yet.
>>
>> The Block Device is an old way of handling a blacklist in the host. Using Add Device is the new method of actually utilizing a whitelist. We also use that for incoming connections now and even in the case of BR/EDR.
>>
>> Using the controller whitelist filtering for LE is an optimization to wake the host up less often. In case of LE and we have no RPAs, we actually use the controller whitelist. Have a look at the current code and test it. Then you see what we are actually doing.
>>
>> I am talking about LE devices. There is only one whitelist in the controller. If you use it for scanning and advertising than it has to be shared. Meaning if you want to connect to device A and want accept connection from device B, then you need to put both devices in the whitelist and enable scanning and advertising at the same time.
>
> This is clearer to me now, thank you for taking the time to explain.
>
> If I recap, the idea would be to add a possible Action parameter to the
> Add Device command, let's say 0x03 "Allow connection" ( to be changed ):
> - For BR/EDR, it would have the same meaning as 0x01
> - For LE, it would mean that we would both scan and advertise
> as connectable, with the advertising filter policy set to only allow
> connection requests from whitelisted devices
do not intermix scanning with advertising for Type 0x03 here. It is mainly about advertising. It means you allow device A to connect to you. For that to do, you have to advertise. The controller whitelist is really only to filter out CONNECT_REQ (and potentially SCAN_REQ) PDU types.
I think the only careful thing here is to handle the advertising instances we have already in place for doing advertising. So maybe Type 0x03 would only control the case of imposing the whitelist and nothing else. And in that case we would not even bother enabling this for BR/EDR at all.
> We set the controller's whitelist as hci_dev->whitelist and handle false
> positives in the case we have a LL_CONNECT_REQ from a device that has
> action 0x01.
Yes, in case you have have done Add Device with Type 0x02 for example, you will be woken up (aka being connected to) from devices that you not added via Type 0x03. These ones just need to be disconnected. However that really only happens if you plan to be peripheral and central role at the same time.
Regards
Marcel
> >>> I would like to discuss a use-case that I encountered on my project, and
> >>> for which I cannot find a right way to do it with mgmt API.
> >>>
> >>> I have a controller, the 88W8887 that I need to set in 'wakeup host' mode.
> >>>
> >>> I put my host in suspend-to-mem, and the controller toggles a GPIO to wake
> >>> it up under certain circumstances, including a Low Energy connection.
> >>>
> >>> To do that, I need to :
> >>> - configure precisely my advertising intervals, to be in low duty
> >>> cycle advertising, with a long interval between advertisements
> >>> - configure the filter policy, to only process connection
> >>> requests from whitelisted devices ( we want only whitelisted
> >>> devices to be able to wakeup our system ).
> >>>
> >>> I previously did that with the HCI lib in my C program, and submitted a
> >>> patch to the hci lib, to add the le_set_advertising_parameters to the lib.
> >>>
> >>> I used the following HCI commands :
> >>> - LE clear whitelist ( OCF 0x0010 )
> >>> - LE Add device to whitelist ( OCF 0x0011 )
> >>> - LE Set advertising parameters ( OCF 0x0006 )
> >>> - LE Set advertise enable ( OCF 0x000A )
> >>>
> >>> It turns out this is not the right approach, Johan Hedberg explained to me
> >>> on IRC that the hci lib was not intended to be used by external programs.
> >>>
> >>> Therefore, I'm looking for a way to do it using the mgmt API, but I can't
> >>> find a way to :
> >>> - Manipulate the whitelist
> >>> - Configure advertising intervals
> >>> - Configure the filter policy
> >>>
> >>> If I missed something in the mgmt API that would allow me to do that, please
> >>> point it to me. If these are some missing features, I am willing to spend some
> >>> time working on it.
> >>
> >> it sounds to me that Add Device with type 0x01 is actually what we really wanted to support here. We currently use that for directed connections. So maybe we introduce a type 0x03 which has different meaning on LE compared to 0x01, but for BR/EDR it would actually result in 0x03 defining the incoming connections type for both bearers. On the other hand, is anybody actually using type 0x01 for LE?
> >>
> >> So only tricky part is that when using the whitelist for limiting LL_CONNECT_REQ processing is that we can then not background scan with a whitelist. Since that list might be different. So this is something we need to figure out on what chips actually do here. Or we have to create some combined whitelist and accept false positives that we handle in the host then.
> >
> > I get what you mean for Add Device with Action 0x03, that would fit my needs.
> >
> > I think however that there needs to be a way to specify if we take the
> > whitelist into account while scanning of advertising in connectable mode.
>
> that is clearly not a parameter that we are exposing we are mgmt. The scanning policy is an internal detail.
>
> > I fail to see when we should take the whitelist into account in the current
> > workflows proposed by the API. I get that blocking with Block Device
> > establishes a blacklist, that Add Device could be used to "whitelist" a
> > device, but I think there needs to be a way to set a mode where only
> > whitelisted devices are taken into account for discovery and connection.
> >
> > Sorry if this is unclear, I don't have a full understanding of all the
> > mecanisms yet.
>
> The Block Device is an old way of handling a blacklist in the host. Using Add Device is the new method of actually utilizing a whitelist. We also use that for incoming connections now and even in the case of BR/EDR.
>
> Using the controller whitelist filtering for LE is an optimization to wake the host up less often. In case of LE and we have no RPAs, we actually use the controller whitelist. Have a look at the current code and test it. Then you see what we are actually doing.
>
> I am talking about LE devices. There is only one whitelist in the controller. If you use it for scanning and advertising than it has to be shared. Meaning if you want to connect to device A and want accept connection from device B, then you need to put both devices in the whitelist and enable scanning and advertising at the same time.
This is clearer to me now, thank you for taking the time to explain.
If I recap, the idea would be to add a possible Action parameter to the
Add Device command, let's say 0x03 "Allow connection" ( to be changed ):
- For BR/EDR, it would have the same meaning as 0x01
- For LE, it would mean that we would both scan and advertise
as connectable, with the advertising filter policy set to only allow
connection requests from whitelisted devices
We set the controller's whitelist as hci_dev->whitelist and handle false
positives in the case we have a LL_CONNECT_REQ from a device that has
action 0x01.
I hope I got it right this time :)
Thanks again for your time,
Maxime
Hi Maxime,
>>> I would like to discuss a use-case that I encountered on my project, and
>>> for which I cannot find a right way to do it with mgmt API.
>>>
>>> I have a controller, the 88W8887 that I need to set in 'wakeup host' mode.
>>>
>>> I put my host in suspend-to-mem, and the controller toggles a GPIO to wake
>>> it up under certain circumstances, including a Low Energy connection.
>>>
>>> To do that, I need to :
>>> - configure precisely my advertising intervals, to be in low duty
>>> cycle advertising, with a long interval between advertisements
>>> - configure the filter policy, to only process connection
>>> requests from whitelisted devices ( we want only whitelisted
>>> devices to be able to wakeup our system ).
>>>
>>> I previously did that with the HCI lib in my C program, and submitted a
>>> patch to the hci lib, to add the le_set_advertising_parameters to the lib.
>>>
>>> I used the following HCI commands :
>>> - LE clear whitelist ( OCF 0x0010 )
>>> - LE Add device to whitelist ( OCF 0x0011 )
>>> - LE Set advertising parameters ( OCF 0x0006 )
>>> - LE Set advertise enable ( OCF 0x000A )
>>>
>>> It turns out this is not the right approach, Johan Hedberg explained to me
>>> on IRC that the hci lib was not intended to be used by external programs.
>>>
>>> Therefore, I'm looking for a way to do it using the mgmt API, but I can't
>>> find a way to :
>>> - Manipulate the whitelist
>>> - Configure advertising intervals
>>> - Configure the filter policy
>>>
>>> If I missed something in the mgmt API that would allow me to do that, please
>>> point it to me. If these are some missing features, I am willing to spend some
>>> time working on it.
>>
>> it sounds to me that Add Device with type 0x01 is actually what we really wanted to support here. We currently use that for directed connections. So maybe we introduce a type 0x03 which has different meaning on LE compared to 0x01, but for BR/EDR it would actually result in 0x03 defining the incoming connections type for both bearers. On the other hand, is anybody actually using type 0x01 for LE?
>>
>> So only tricky part is that when using the whitelist for limiting LL_CONNECT_REQ processing is that we can then not background scan with a whitelist. Since that list might be different. So this is something we need to figure out on what chips actually do here. Or we have to create some combined whitelist and accept false positives that we handle in the host then.
>
> I get what you mean for Add Device with Action 0x03, that would fit my needs.
>
> I think however that there needs to be a way to specify if we take the
> whitelist into account while scanning of advertising in connectable mode.
that is clearly not a parameter that we are exposing we are mgmt. The scanning policy is an internal detail.
> I fail to see when we should take the whitelist into account in the current
> workflows proposed by the API. I get that blocking with Block Device
> establishes a blacklist, that Add Device could be used to "whitelist" a
> device, but I think there needs to be a way to set a mode where only
> whitelisted devices are taken into account for discovery and connection.
>
> Sorry if this is unclear, I don't have a full understanding of all the
> mecanisms yet.
The Block Device is an old way of handling a blacklist in the host. Using Add Device is the new method of actually utilizing a whitelist. We also use that for incoming connections now and even in the case of BR/EDR.
Using the controller whitelist filtering for LE is an optimization to wake the host up less often. In case of LE and we have no RPAs, we actually use the controller whitelist. Have a look at the current code and test it. Then you see what we are actually doing.
> So when you say "accept false positives that we handle in the host", you
> are talking about a BR/EDR device that is not whitelisted but that might
> have been seen by the controller since it only takes LE addresses into
> account in its whitelist ?
I am talking about LE devices. There is only one whitelist in the controller. If you use it for scanning and advertising than it has to be shared. Meaning if you want to connect to device A and want accept connection from device B, then you need to put both devices in the whitelist and enable scanning and advertising at the same time.
Regards
Marcel
Hi Marcel,
Thanks for the answer,
> Hi Maxime,
>
> > I would like to discuss a use-case that I encountered on my project, and
> > for which I cannot find a right way to do it with mgmt API.
> >
> > I have a controller, the 88W8887 that I need to set in 'wakeup host' mode.
> >
> > I put my host in suspend-to-mem, and the controller toggles a GPIO to wake
> > it up under certain circumstances, including a Low Energy connection.
> >
> > To do that, I need to :
> > - configure precisely my advertising intervals, to be in low duty
> > cycle advertising, with a long interval between advertisements
> > - configure the filter policy, to only process connection
> > requests from whitelisted devices ( we want only whitelisted
> > devices to be able to wakeup our system ).
> >
> > I previously did that with the HCI lib in my C program, and submitted a
> > patch to the hci lib, to add the le_set_advertising_parameters to the lib.
> >
> > I used the following HCI commands :
> > - LE clear whitelist ( OCF 0x0010 )
> > - LE Add device to whitelist ( OCF 0x0011 )
> > - LE Set advertising parameters ( OCF 0x0006 )
> > - LE Set advertise enable ( OCF 0x000A )
> >
> > It turns out this is not the right approach, Johan Hedberg explained to me
> > on IRC that the hci lib was not intended to be used by external programs.
> >
> > Therefore, I'm looking for a way to do it using the mgmt API, but I can't
> > find a way to :
> > - Manipulate the whitelist
> > - Configure advertising intervals
> > - Configure the filter policy
> >
> > If I missed something in the mgmt API that would allow me to do that, please
> > point it to me. If these are some missing features, I am willing to spend some
> > time working on it.
>
> it sounds to me that Add Device with type 0x01 is actually what we really wanted to support here. We currently use that for directed connections. So maybe we introduce a type 0x03 which has different meaning on LE compared to 0x01, but for BR/EDR it would actually result in 0x03 defining the incoming connections type for both bearers. On the other hand, is anybody actually using type 0x01 for LE?
>
> So only tricky part is that when using the whitelist for limiting LL_CONNECT_REQ processing is that we can then not background scan with a whitelist. Since that list might be different. So this is something we need to figure out on what chips actually do here. Or we have to create some combined whitelist and accept false positives that we handle in the host then.
I get what you mean for Add Device with Action 0x03, that would fit my needs.
I think however that there needs to be a way to specify if we take the
whitelist into account while scanning of advertising in connectable mode.
I fail to see when we should take the whitelist into account in the current
workflows proposed by the API. I get that blocking with Block Device
establishes a blacklist, that Add Device could be used to "whitelist" a
device, but I think there needs to be a way to set a mode where only
whitelisted devices are taken into account for discovery and connection.
Sorry if this is unclear, I don't have a full understanding of all the
mecanisms yet.
So when you say "accept false positives that we handle in the host", you
are talking about a BR/EDR device that is not whitelisted but that might
have been seen by the controller since it only takes LE addresses into
account in its whitelist ?
Thanks,
Maxime
Hi Maxime,
> I would like to discuss a use-case that I encountered on my project, and
> for which I cannot find a right way to do it with mgmt API.
>
> I have a controller, the 88W8887 that I need to set in 'wakeup host' mode.
>
> I put my host in suspend-to-mem, and the controller toggles a GPIO to wake
> it up under certain circumstances, including a Low Energy connection.
>
> To do that, I need to :
> - configure precisely my advertising intervals, to be in low duty
> cycle advertising, with a long interval between advertisements
> - configure the filter policy, to only process connection
> requests from whitelisted devices ( we want only whitelisted
> devices to be able to wakeup our system ).
>
> I previously did that with the HCI lib in my C program, and submitted a
> patch to the hci lib, to add the le_set_advertising_parameters to the lib.
>
> I used the following HCI commands :
> - LE clear whitelist ( OCF 0x0010 )
> - LE Add device to whitelist ( OCF 0x0011 )
> - LE Set advertising parameters ( OCF 0x0006 )
> - LE Set advertise enable ( OCF 0x000A )
>
> It turns out this is not the right approach, Johan Hedberg explained to me
> on IRC that the hci lib was not intended to be used by external programs.
>
> Therefore, I'm looking for a way to do it using the mgmt API, but I can't
> find a way to :
> - Manipulate the whitelist
> - Configure advertising intervals
> - Configure the filter policy
>
> If I missed something in the mgmt API that would allow me to do that, please
> point it to me. If these are some missing features, I am willing to spend some
> time working on it.
it sounds to me that Add Device with type 0x01 is actually what we really wanted to support here. We currently use that for directed connections. So maybe we introduce a type 0x03 which has different meaning on LE compared to 0x01, but for BR/EDR it would actually result in 0x03 defining the incoming connections type for both bearers. On the other hand, is anybody actually using type 0x01 for LE?
So only tricky part is that when using the whitelist for limiting LL_CONNECT_REQ processing is that we can then not background scan with a whitelist. Since that list might be different. So this is something we need to figure out on what chips actually do here. Or we have to create some combined whitelist and accept false positives that we handle in the host then.
Regards
Marcel