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Date: Fri, 21 Jan 2011 09:38:11 -0500
Message-ID: <AANLkTimFqxYJ_wNgfthjCRfarF83+o5F4KZFjQ7hz3P_@mail.gmail.com>
Subject: Re: How to close bluetooth? Using rfkill?
From: zhangfei gao <zhangfei.gao@gmail.com>
To: linux-bluetooth@vger.kernel.org, Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
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On Fri, Jan 21, 2011 at 12:51 AM, zhangfei gao <zhangfei.gao@gmail.com> wrote:
> Hi Johan,
>
> Is there any general method to open/close bluetooth, using rfkill or
> pm_runtime_get/put_* API.
>
> Currently we use rfkill to close bluetooth, however we met dead lock
> issue, for mutex_lock(&rfkill_global_mutex).
> So we use workaround to rmmod bt.ko first, or revert the rfkill patch
> in hci_core.c.
>
> BT/WIFI device have chip select pin, we register one rfkill with
> sd8x_set_block, and control chip select pin to open/close bt/wifi/fm.
> for example:
> rfkill unblock bluetooth to open bt
> rfkill block bluetooth to close bt
>
> When "rfkill block bluetooth",
> rfkill_fop_write->mutex_lock(&rfkill_global_mutex)->rfkill_set_block->sd8x_set_block->waiting
> for card is freed.
> BT driver will call
> hci_unregister_dev->rfkill_unregister->mutex_lock(&rfkill_global_mutex);
> So mutex_lock(&rfkill_global_mutex) will be dead locked.
>
> If so, do we have to use other method to control chip select pin to
> control bt power, such as pm_runtime_get/put_* API.
>
> Thanks in advance.
>

Hi, Marcel

Do you have some suggestion?
When we use "rfkill block bluetooth" to disable bt, bt driver call
hci_unregister_dev to free driver.
The dead lock happens for acquiring mutex_lock(&rfkill_global_mutex).
One in rfkill_unregister from hci_unregister_dev, the other in
rfkill_fop_write from "rfkill block bluetooth" .
Is this the correct method to open/close bluetooth.

Thanks