linux-kernel - Re: [PATCH v1 1/5] Bluetooth: advmon offload MSFT add rssi support

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Message-ID: <CAJQfnxGOg_b+DkqVuUh0jqQL4VmY0ijB4kEmfGg92K3D_KbNZQ@mail.gmail.com>
Date:   Mon, 7 Dec 2020 18:48:22 +0800
From:   Archie Pusaka <apusaka@...gle.com>
To:     Marcel Holtmann <marcel@...tmann.org>
Cc:     linux-bluetooth <linux-bluetooth@...r.kernel.org>,
        CrosBT Upstreaming <chromeos-bluetooth-upstreaming@...omium.org>,
        Archie Pusaka <apusaka@...omium.org>,
        Miao-chen Chou <mcchou@...omium.org>,
        Yun-Hao Chung <howardchung@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>
Subject: Re: [PATCH v1 1/5] Bluetooth: advmon offload MSFT add rssi support

Hi Marcel,

On Mon, 7 Dec 2020 at 17:57, Marcel Holtmann <marcel@...tmann.org> wrote:
>
> Hi Archie,
>
> >>>>> MSFT needs rssi parameter for monitoring advertisement packet,
> >>>>> therefore we should supply them from mgmt.
> >>>>>
> >>>>> Signed-off-by: Archie Pusaka <apusaka@...omium.org>
> >>>>> Reviewed-by: Miao-chen Chou <mcchou@...omium.org>
> >>>>> Reviewed-by: Yun-Hao Chung <howardchung@...gle.com>
> >>>>
> >>>> I don’t need any Reviewed-by if they are not catching an obvious user API breakage.
> >>>>
> >>>>> ---
> >>>>>
> >>>>> include/net/bluetooth/hci_core.h | 9 +++++++++
> >>>>> include/net/bluetooth/mgmt.h     | 9 +++++++++
> >>>>> net/bluetooth/mgmt.c             | 8 ++++++++
> >>>>> 3 files changed, 26 insertions(+)
> >>>>>
> >>>>> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> >>>>> index 9873e1c8cd16..42d446417817 100644
> >>>>> --- a/include/net/bluetooth/hci_core.h
> >>>>> +++ b/include/net/bluetooth/hci_core.h
> >>>>> @@ -246,8 +246,17 @@ struct adv_pattern {
> >>>>>     __u8 value[HCI_MAX_AD_LENGTH];
> >>>>> };
> >>>>>
> >>>>> +struct adv_rssi_thresholds {
> >>>>> +     __s8 low_threshold;
> >>>>> +     __s8 high_threshold;
> >>>>> +     __u16 low_threshold_timeout;
> >>>>> +     __u16 high_threshold_timeout;
> >>>>> +     __u8 sampling_period;
> >>>>> +};
> >>>>> +
> >>>>> struct adv_monitor {
> >>>>>     struct list_head patterns;
> >>>>> +     struct adv_rssi_thresholds rssi;
> >>>>>     bool            active;
> >>>>>     __u16           handle;
> >>>>> };
> >>>>> diff --git a/include/net/bluetooth/mgmt.h b/include/net/bluetooth/mgmt.h
> >>>>> index d8367850e8cd..dc534837be0e 100644
> >>>>> --- a/include/net/bluetooth/mgmt.h
> >>>>> +++ b/include/net/bluetooth/mgmt.h
> >>>>> @@ -763,9 +763,18 @@ struct mgmt_adv_pattern {
> >>>>>     __u8 value[31];
> >>>>> } __packed;
> >>>>>
> >>>>> +struct mgmt_adv_rssi_thresholds {
> >>>>> +     __s8 high_threshold;
> >>>>> +     __le16 high_threshold_timeout;
> >>>>> +     __s8 low_threshold;
> >>>>> +     __le16 low_threshold_timeout;
> >>>>> +     __u8 sampling_period;
> >>>>> +} __packed;
> >>>>> +
> >>>>> #define MGMT_OP_ADD_ADV_PATTERNS_MONITOR      0x0052
> >>>>> struct mgmt_cp_add_adv_patterns_monitor {
> >>>>>     __u8 pattern_count;
> >>>>> +     struct mgmt_adv_rssi_thresholds rssi;
> >>>>>     struct mgmt_adv_pattern patterns[];
> >>>>> } __packed;
> >>>>
> >>>> This is something we can not do. It breaks an userspace facing API. Is the mgmt opcode 0x0052 in an already released kernel?
> >>>
> >>> Yes, the opcode does exist in an already released kernel.
> >>>
> >>> The DBus method which accesses this API is put behind the experimental
> >>> flag, therefore we expect they are flexible enough to support changes.
> >>> Previously, we already had a discussion in an email thread with the
> >>> title "Offload RSSI tracking to controller", and the outcome supports
> >>> this change.
> >>>
> >>> Here is an excerpt of the discussion.
> >>
> >> it doesn’t matter. This is fixed API now and so we can not just change it. The argument above is void. What matters if it is in already released kernel.
> >
> > If that is the case, do you have a suggestion to allow RSSI to be
> > considered when monitoring advertisement? Would a new MGMT opcode with
> > these parameters suffice?
>
> its the only way.

I will make the necessary changes. Thanks for the confirmation.

Regards,
Archie

>
> Regards
>
> Marcel
>