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Date: Wed, 28 May 2014 11:45:13 +0300
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Subject: Re: [RFC] Bluetooth: Keep master role when SCO or eSCO is active
From: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
To: Kiran Kumar Raparthy <kiran.kumar@linaro.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"hyungseoung.yoo" <hyungseoung.yoo@samsung.com>, Marcel Holtmann <marcel@holtmann.org>,
	Gustavo Padovan <gustavo@padovan.org>, Johan Hedberg <johan.hedberg@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	"open list:BLUETOOTH SUBSYSTEM" <linux-bluetooth@vger.kernel.org>,
	"open list:NETWORKING [GENERAL]" <netdev@vger.kernel.org>, Android Kernel Team <kernel-team@android.com>,
	John Stultz <john.stultz@linaro.org>, Jaikumar Ganesh <jaikumarg@android.com>
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List-ID: <linux-bluetooth.vger.kernel.org>

Hi,

On Wed, May 28, 2014 at 8:56 AM, Kiran Kumar Raparthy
<kiran.kumar@linaro.org> wrote:
> From: "hyungseoung.yoo" <hyungseoung.yoo@samsung.com>
>
> Preserve the master role when SCO or eSCO is active
> as this improves compatability with lots of
> headset and chipset combinations.
>
> This is one of the number of patches from the Android AOSP
> common.git tree, which is used on almost all Android devices.
> It looks like it would improve support for compatibility with
> lot of headset,so I wanted to submit it for review to see
> if it should go upstream.
>
> Cc: Marcel Holtmann <marcel@holtmann.org> (maintainer:BLUETOOTH SUBSYSTEM)
> Cc: Gustavo Padovan <gustavo@padovan.org> (maintainer:BLUETOOTH SUBSYSTEM)
> Cc: Johan Hedberg <johan.hedberg@gmail.com> (maintainer:BLUETOOTH SUBSYSTEM)
> Cc: "David S. Miller" <davem@davemloft.net> (maintainer:NETWORKING [GENERAL])
> Cc: linux-bluetooth@vger.kernel.org (open list:BLUETOOTH SUBSYSTEM)
> Cc: netdev@vger.kernel.org (open list:NETWORKING [GENERAL])
> Cc: linux-kernel@vger.kernel.org (open list)
> Cc: Android Kernel Team <kernel-team@android.com>
> Cc: John Stultz <john.stultz@linaro.org>
> Signed-off-by: hyungseoung.yoo <hyungseoung.yoo@samsung.com>
> Signed-off-by: Jaikumar Ganesh <jaikumarg@android.com>
> [kiran: Added context to commit message]
> Signed-off-by: Kiran Raparthy <kiran.kumar@linaro.org>
> ---
>  net/bluetooth/hci_event.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 15010a2..6f944d5 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -1915,6 +1915,15 @@ unlock:
>         hci_conn_check_pending(hdev);
>  }
>
> +static inline bool is_sco_active(struct hci_dev *hdev)
> +{
> +       if (hci_conn_hash_lookup_state(hdev, SCO_LINK, BT_CONNECTED) ||
> +                       (hci_conn_hash_lookup_state(hdev, ESCO_LINK,
> +                                                   BT_CONNECTED)))
> +               return true;
> +       return false;
> +}
> +
>  static void hci_conn_request_evt(struct hci_dev *hdev, struct sk_buff *skb)
>  {
>         struct hci_ev_conn_request *ev = (void *) skb->data;
> @@ -1961,7 +1970,8 @@ static void hci_conn_request_evt(struct hci_dev *hdev, struct sk_buff *skb)
>
>                         bacpy(&cp.bdaddr, &ev->bdaddr);
>
> -                       if (lmp_rswitch_capable(hdev) && (mask & HCI_LM_MASTER))
> +                       if (lmp_rswitch_capable(hdev) && ((mask & HCI_LM_MASTER)
> +                                               || is_sco_active(hdev)))
>                                 cp.role = 0x00; /* Become master */
>                         else
>                                 cp.role = 0x01; /* Remain slave */
> --
> 1.8.2.1

I guess the real issue is the possibility of creating a scatternet if
you have more than one connection, I will send a patch for scatternet
shortly but that does not guarantee the remote device wont reject it.


-- 
Luiz Augusto von Dentz