Received-SPF: pass (google.com: domain of linux-bluetooth-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <319b239d-3739-63e9-9fe4-f8b4215097b2@vontaene.de>
In-Reply-To: <319b239d-3739-63e9-9fe4-f8b4215097b2@vontaene.de>
From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Mon, 27 Apr 2020 10:18:52 -0700
Message-ID: <CABBYNZ+1DytMUg6B7CrGNaNTz55_a6EDQAL58gD_xq4upz0Ctw@mail.gmail.com>
Subject: Re: HID device with multiple collections does not work
To:     Erik Andresen <erik@vontaene.de>
Cc:     "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

Hi Erik,

On Thu, Apr 23, 2020 at 11:07 AM Erik Andresen <erik@vontaene.de> wrote:
>
> Hi,
>
>
> I have a simple bluetooth hid device which does work in Android but not w=
ith Linux 4.19/Bluez 5. It does have two collections in its hid description=
:
> 0xA1, 0x01,        // Collection (Application)
> 0x85, 0x02,        //   Report ID (2)
> (...)
> 0xC0,              // End Collection
> 0xA1, 0x01,        // Collection (Application)
> 0x85, 0x01,        //   Report ID (1)
> (...)
> 0xC0,              // End Collection
>
> Complete description is attached.
>
> Since there are multiple collections I understand that every report has t=
o be prefixed with the id, so I send
> [2,0,0,0x52,0,0,0,0,0] (9 bytes) for the keycode 0x52, ID is 2.
>
> Output from btmon is:
> > ACL Data RX: Handle 3585 flags 0x02 dlen 16                            =
                                                                           =
                                                                           =
                          #2072 [hci0] 485.047387
>        ATT: Handle Value Notification (0x1b) len 11
>          Handle: 0x0015
>            Data: 020000520000000000
>
> This looks good for me so far, unfortunately Linux does not pick it up, i=
n dmesg I get:
> drivers/hid/hid-core.c: undefined report_id 0 received
>
> cat /sys/kernel/debug/hid/0005:0000:0000.000=C2=AD3/events # gives me:
> report (size 10) (numbered) =3D 00 02 00 00 52 00 00 00 00 00
> so I get 10 bytes instead the 9 I send
>
> So far I traced it to hog-lib.c, report_value_cb() of bluez where this ex=
tra 0 is prepended in the if (hog->has_report_id) block.
> report->id is 0 at this point. If I skip this extra addition of the zero =
or manually set id=3D2 here it works as expected. Does someone has an idea =
what I do wrong or what I'm missing?

Afaik each report ID will need to have its own characteristic, at
least that is how HIDS has put the spec, but if I got you right the
report->id is never initialized on report_reference_cb so this might
be how Android is detecting if there is a report ID or not, we should
be able to confiirm this if we have access to the HCI trace when
discovering the services.

> greetings,
> Erik Andresen


--=20
Luiz Augusto von Dentz