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Subject: Re: [PATCH 3/3] Bluetooth: Avoid WARN splat due to missing GPIOLIB
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Lukas Wunner <lukas@wunner.de>,
        Marcel Holtmann <marcel@holtmann.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        Linus Walleij <linus.walleij@linaro.org>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>,
        Frederic Danis <frederic.danis.oss@gmail.com>,
        Loic Poulain <loic.poulain@linaro.org>,
        Hans de Goede <hdegoede@redhat.com>,
        Max Shavrick <mxms@me.com>, Leif Liddy <leif.liddy@gmail.com>,
        Daniel Roschka <danielroschka@phoenitydawn.de>,
        Ronald Tschalaer <ronald@innovation.ch>,
        "Peter Y. Chuang" <peteryuchuang@gmail.com>,
        linux-bluetooth@vger.kernel.org
Date: Thu, 28 Dec 2017 10:41:17 +0200
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         <9ef8be4ef80c38b693e5755c738a88de9c907944.1514143015.git.lukas@wunner.de>
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On Tue, 2017-12-26 at 17:07 +0200, Lukas Wunner wrote:
> Loading hci_bcm with CONFIG_GPIOLIB=n results in the following splat
> when calling gpiod_to_irq() from bcm_get_resources():
> 
>     WARNING: CPU: 0 PID: 1006 at ./include/linux/gpio/consumer.h:450
> bcm_get_resources+0x50/0x80
>     CPU: 0 PID: 1006 Comm: kworker/u8:4 Tainted:
> G       A         4.15.0-rc4custom+ #4
>     Hardware name: Apple Inc. MacBook8,1/Mac-BE0E8AC46FE800CC, BIOS
> MB81.88Z.0168.B00.1708080033 08/08/2017
>     Call Trace:
>     bcm_serdev_probe+0x8b/0xc0
>     driver_probe_device+0x202/0x310
>     __driver_attach+0x85/0x90
>     ? driver_probe_device+0x310/0x310
>     bus_for_each_dev+0x57/0x80
>     async_run_entry_fn+0x2c/0xd0
>     process_one_work+0x1d2/0x3d0
>     worker_thread+0x26/0x3c0
>     ? process_one_work+0x3d0/0x3d0
>     kthread+0x10c/0x130
>     ? kthread_create_on_node+0x40/0x40
>     ret_from_fork+0x1f/0x30
> 
> We could call gpiod_to_irq() only if IS_ENABLED(CONFIG_GPIOLIB) but
> without GPIOLIB, the driver's power saving features can't be used,
> so selecting GPIOLIB seems more appropriate.
> 
> The same issue is present in hci_intel.c and hci_nokia.c, fix those up
> as well.
> 
> Reported-by: Max Shavrick <mxms@me.com>
> Signed-off-by: Lukas Wunner <lukas@wunner.de>
> ---
>  drivers/bluetooth/Kconfig | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/bluetooth/Kconfig b/drivers/bluetooth/Kconfig
> index 45a2f59cd935..41932f0e68d0 100644
> --- a/drivers/bluetooth/Kconfig
> +++ b/drivers/bluetooth/Kconfig
> @@ -110,6 +110,7 @@ config BT_HCIUART_NOKIA
>  	depends on PM
>  	select BT_HCIUART_H4
>  	select BT_BCM
> +	select GPIOLIB

This is wrong solution. GPIOLIB is meant for GPIO providers, not
consumers.

That's why after I did BT support for Intel MID (commit d4d96990)
the necessity of exporting gpiod_add_lookup_table() had been arisen
(commit 020e0b1c8f19f).

+Cc Linus W

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy