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Date: Mon, 14 Sep 2009 19:52:31 +0800
Message-ID: <113d36d80909140452jb808a2bub393aae7307c7450@mail.gmail.com>
Subject: can we disable/enable eSCO by using setsockopt of sco socket?
From: Lan Zhu <zhu.lan.cn@gmail.com>
To: linux-bluetooth@vger.kernel.org
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Sender: linux-bluetooth-owner@vger.kernel.org
List-ID: <linux-bluetooth.vger.kernel.org>

Hi Marcel,

When we connect a SCO socket, BlueZ decides whether to connect SCO or
eSCO type according to the remote feature. If the remote device
declares supporting eSCO in the remote feature, BlueZ will select eSCO
type to connect with it.

But in fact  there are some old carkits or headsets which are only
support SCO but wrongly declare to support eSCO, such as Motorola
HF850 and HS820 which use a very old CSR chip, so we have problem to
create sco connection with them.

We thought a method to resolve this issue, which is force to create
SCO type connection if we find the HFP version of one remote device is
less than 1.2. So we need a method to control the SCO type from user
space. We want to use setsockopt() functon to do that. The code change
in net/bluetooth/sco.c is like below,


@@ -653,12 +653,25 @@ static int sco_sock_setsockopt(struct socket *sock, int le
 {
       struct sock *sk = sock->sk;
       int err = 0;
+       u32 opt;

       BT_DBG("sk %p", sk);

       lock_sock(sk);

+       if (level != SOL_SCO) {
+               err = -ENOPROTOOPT;
+               return err;
+       }
+
       switch (optname) {
+       case BT_DISABLE_ESCO:
+               if (get_user(opt, (u32 __user *) optval)) {
+                       err = -EFAULT;
+                       break;
+               }
+               disable_esco = opt;
+               break;
       default:
               err = -ENOPROTOOPT;
               break;


Then, in the user space, we can call setsockopt(fd, SOL_SCO,
BT_DISABLE_ESCO, &disabled, sizeof(disabled)) to force to connect SCO.

Do you agree with this change?

Thanks,
Zhu Lan