Return-Path: <foo00@h08.hostsharing.net>
Date: Thu, 28 Dec 2017 10:18:05 +0100
From: Lukas Wunner <lukas@wunner.de>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Marcel Holtmann <marcel@holtmann.org>,
	Johan Hedberg <johan.hedberg@gmail.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	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
Subject: Re: [PATCH 3/3] Bluetooth: Avoid WARN splat due to missing GPIOLIB
Message-ID: <20171228091805.GA1559@wunner.de>
References: <5e3106d673c3c41bf92c91f1f43bf30682511366.1514143015.git.lukas@wunner.de>
 <9ef8be4ef80c38b693e5755c738a88de9c907944.1514143015.git.lukas@wunner.de>
 <1514450477.7000.302.camel@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
In-Reply-To: <1514450477.7000.302.camel@linux.intel.com>
List-ID: <linux-bluetooth.vger.kernel.org>

On Thu, Dec 28, 2017 at 10:41:17AM +0200, Andy Shevchenko wrote:
> 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).

Hm okay, Documentation/gpio/consumer.txt says:

    Guidelines for GPIOs consumers
    ==============================

    Drivers that can't work without standard GPIO calls should have
    Kconfig entries that depend on GPIOLIB.

So a "depends on GPIOLIB" would be more appropriate, right?

Thanks,

Lukas