Hi Marcel,
On Wed, Apr 22, 2020 at 10:33 AM Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote:
>
> Hi Miao-chen,
>
> > This describes the following commands.
> > - Add Advertisement Patterns Monitor
> > - Remove Advertisement Monitors
> > Note that the content of a monitor can differ based on its type. For now we
> > introduce only pattern-based monitor, so you may find that unlike the
> > command of removing monitor(s), the Add command is tied to a specific type.
> > ---
> >
> > Changes in v2:
> > - Combine commands to remove one monitor and remove all monitors. The
> > refined command takes multiple handles and an extra field to indicate
> > whether to remove all monitors.
> >
> > doc/mgmt-api.txt | 83 ++++++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 83 insertions(+)
> >
> > diff --git a/doc/mgmt-api.txt b/doc/mgmt-api.txt
> > index 39f23c456..d5d402361 100644
> > --- a/doc/mgmt-api.txt
> > +++ b/doc/mgmt-api.txt
> > @@ -3138,6 +3138,89 @@ Read Security Information Command
> > Invalid Index
> >
> >
> > +Add Advertisement Patterns Monitor Command
> > +=========================================
>
> I wonder if we do Add Advertisement Monitor Pattern or Add Advertisement Monitor With Pattern.
>
> > +
> > + Command Code: 0x0049
> > + Controller Index: <controller id>
> > + Command Parameters: Pattern_count (1 Octets)
> > + Pattern1 {
> > + AD_Data_Type (1 Octet)
> > + Offset (1 Octet)
> > + Length (1 Octet)
> > + Value (variable length)
> > + }
> > + Pattern2 { }
> > + ...
> > + Return Parameters: Monitor_Handle (8 Octets)
>
> Why 8 Octets? How many do you expect? I would do 16-bit.
My thought was that the number of monitor slots may not be fixed for
different extensions, so the idea was to have one-time handles which
will not be reused once a monitor was removed. If reusing the slots is
a preferable approach, given that Android and Microsoft extensions use
uint8 for indexing filters, we can use either uint16 or uint32 as the
index. I will put uint16 for now.
>
> > +
> > + This command is used to add an advertisement monitor whose filtering
> > + conditions are patterns. The kernel would track the number of registered
> > + monitors to determine whether to perform LE scanning while there is
> > + ongoing LE scanning for other intentions, such as auto-reconnection and
> > + discovery session. If the controller supports Microsoft HCI extension,
> > + the kernel would offload the content filtering to the controller in
> > + order to reduce power consumption; otherwise the kernel ignore the
> > + content of the monitor. Note that if the there are more than one
> > + patterns, OR logic would applied among patterns during filtering. In
> > + other words, any advertisement matching at least one pattern in a given
> > + monitor would be considered as a match.
> > +
> > + A pattern contain the following fields.
> > + AD_Data_Type Advertising Data Type. The possible values are
> > + defined in Core Specification Supplement.
> > + Offset The start index where pattern matching shall be
> > + performed with in the AD data.
> > + Length The length of the pattern value in bytes.
> > + Value The value of the pattern in bytes.
> > +
> > + Here is an example of a pattern.
> > + {
> > + 0x16, // Service Data - 16-bit UUID
> > + 0x02, // Skip the UUID part.
> > + 0x04,
> > + {0x11, 0x22, 0x33, 0x44},
> > + }
> > +
> > + Possible errors: Failed
> > + Busy
> > + Invalid Parameters
> > +
> > +
> > +Remove Advertisement Monitors Command
> > +=====================================
>
> I would have a generic Remove Adveristement Monitor. As requested, I will combine the remove and remove all operations by reserving 0 as a hint for removing all.
>
> > +
> > + Command Code: 0x004A
> > + Controller Index: <controller id>
> > + Command Parameters: Remove_All (1 Octet)
>
> Skip the Remove_All. If you give Monitor_Count == 0, then it will remove all of them. This is how we have done the others.
>
> > + Monitor_Count (2 Octets)
> > + Monitor_Handle[i] (8 Octets)
> > + Return Parameters: Removed_Monitor_Count (2 Octets)
> > + Removed_Monitor_Handle[i] (8 Octets)
>
> Return values are not needed here.
>
> > +
> > + This command is used to remove advertisement monitor(s). The kernel
> > + would remove the monitor(s) with Monitor_Index and update the LE
> > + scanning. If the controller supports Microsoft HCI extension and the
> > + monitor(s) has been offloaded, the kernel would cancel the offloading;
> > + otherwise the kernel takes no further actions other than removing the
> > + monitor(s) from the list.
> > +
> > + Remove_All can be the following values.
> > + Value Operation
> > + -------------------------
> > + 0x00 Removes only the monitors with handles specified
> > + in Monitor_Handle[i], so there must be at least
> > + one handle.
> > + 0x01 Removes all existing monitor(s), so
> > + Monitor_Count must be 0, and Monitor_Handle
> > + must be empty.
> > +
> > + Possible errors: Failed
> > + Busy
> > + Invalid Index
> > + Invalid Parameters
> > +
> > +
> > Command Complete Event
> > ======================
>
> You are missing signals for Monitor Added and Monitor Removed.
Nice catch. I will add them in v3.
>
> And we are also missing a command for reading the basic supported features. Like we do for Advertising as well.
There was a comment made in the past discussion where we can introduce
a new setting(s) in the returned supported_settings of
MGMT_OP_READ_INFO command to indicate the features such as
MGMT_SETTING_HW_FILTERING . But given that there can be multiple
extensions, it may be preferable to have a separate command which
should be extendable.
Thanks,
Miao
