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From: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date: Wed, 1 Mar 2017 12:58:59 +0200
Message-ID: <CABBYNZ+XivaqFmfGvXfkS4vY7WBRHkU9FhpkgYPkaP-4GYArgQ@mail.gmail.com>
Subject: Re: [PATCH v2 3/3] hog: Optionally destroy uHID device when disconnected
To: Juha Kuikka <juha.kuikka@synapse.com>
Cc: "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>,
        Juha Kuikka <juha.kuikka@gmail.com>,
        Petri Gynther <pgynther@google.com>
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Sender: linux-bluetooth-owner@vger.kernel.org
List-ID: <linux-bluetooth.vger.kernel.org>

Hi Juha,

On Wed, Mar 1, 2017 at 3:06 AM, Juha Kuikka <juha.kuikka@synapse.com> wrote:
> Unlink bluetooth classic HID, HoG persists the uHID device after across
> connections. This is fine for stateless devices that require fast reconnections
> but some device utilize hidraw to configure them upon connection and with the
> persisting uHID device, reconnections are hidden from them.
>
> Similarly, applications such as game emulators may be using the presence of the
> HID or the accompanying input event devices to indicate that it is available,
> thus changing behavior.
>
> This patch introduces a configuration option that, when set, destroys the uHID
> device upon disconnection, it gets re-created upon reconnection, just like on
> initial connection.
> ---
>  profiles/input/hog-lib.c | 29 +++++++++++++++++++++++++++++
>  profiles/input/hog-lib.h |  1 +
>  2 files changed, 30 insertions(+)
>
> diff --git a/profiles/input/hog-lib.c b/profiles/input/hog-lib.c
> index dab385f..b2a371e 100644
> --- a/profiles/input/hog-lib.c
> +++ b/profiles/input/hog-lib.c
> @@ -129,6 +129,13 @@ struct gatt_request {
>         void *user_data;
>  };
>
> +static bool uhid_destroy = false;
> +
> +void bt_hog_set_uhid_destroy(bool state)
> +{
> +       uhid_destroy = state;
> +}
> +
>  static struct gatt_request *create_request(struct bt_hog *hog,
>                                                         void *user_data)
>  {
> @@ -1565,6 +1572,25 @@ static void primary_cb(uint8_t status, GSList *services, void *user_data)
>         }
>  }
>
> +static void destroy_uhid(struct bt_hog *hog)
> +{
> +       struct uhid_event ev = {
> +               .type = UHID_DESTROY
> +       };
> +       int err;
> +
> +       if (hog->uhid_created) {
> +               err = bt_uhid_send(hog->uhid, &ev);
> +               if (err < 0) {
> +                       error("bt_uhid_send: %s", strerror(-err));
> +                       return;
> +               }
> +               hog->uhid_created = false;
> +
> +               DBG("HoG destroyed uHID device");
> +       }
> +}
> +
>  bool bt_hog_attach(struct bt_hog *hog, void *gatt)
>  {
>         GSList *l;
> @@ -1651,6 +1677,9 @@ void bt_hog_detach(struct bt_hog *hog)
>         queue_foreach(hog->gatt_op, (void *) cancel_gatt_req, NULL);
>         g_attrib_unref(hog->attrib);
>         hog->attrib = NULL;
> +
> +       if (uhid_destroy)
> +               destroy_uhid(hog);

It probably make sense to check if hog->uhid_created.

>  }
>
>  int bt_hog_set_control_point(struct bt_hog *hog, bool suspend)
> diff --git a/profiles/input/hog-lib.h b/profiles/input/hog-lib.h
> index 415dc63..de8c42f 100644
> --- a/profiles/input/hog-lib.h
> +++ b/profiles/input/hog-lib.h
> @@ -39,3 +39,4 @@ void bt_hog_detach(struct bt_hog *hog);
>
>  int bt_hog_set_control_point(struct bt_hog *hog, bool suspend);
>  int bt_hog_send_report(struct bt_hog *hog, void *data, size_t size, int type);
> +void bt_hog_set_uhid_destroy(bool state);

Ive made this per instance.

> --
> 2.7.4

I would consider doing this in the bt_uhid instance



-- 
Luiz Augusto von Dentz