linux-kernel - Re: [PATCH AUTOSEL for 4.15 099/124] Bluetooth: hci_bcm: Mandate presence of shutdown and device wake GPIO

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Date:   Mon, 19 Mar 2018 19:53:58 +0100
From:   Lukas Wunner <lukas@...ner.de>
To:     Sasha Levin <Alexander.Levin@...rosoft.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Frédéric Danis 
        <frederic.danis.oss@...il.com>,
        Loic Poulain <loic.poulain@...aro.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Marcel Holtmann <marcel@...tmann.org>,
        Stefan Wahren <stefan.wahren@...e.com>
Subject: Re: [PATCH AUTOSEL for 4.15 099/124] Bluetooth: hci_bcm: Mandate
 presence of shutdown and device wake GPIO

On Mon, Mar 19, 2018 at 03:48:50PM +0000, Sasha Levin wrote:
> From: Lukas Wunner <lukas@...ner.de>
> 
> [ Upstream commit 3e81a4ca51a1172253078ca7abd6a91040b8fcf4 ]
>

Unfortunately this commit had to be fixed up with ab2f336cb7e6
("Bluetooth: hci_bcm: Make shutdown and device wake GPIO optional")
by Stefan Wahren (+cc).

Please be sure to apply that one on top.  Thanks!


> Commit 0395ffc1ee05 ("Bluetooth: hci_bcm: Add PM for BCM devices")
> amended this driver to request a shutdown and device wake GPIO on probe,
> but mandated that only one of them need to be present:
> 
> 	/* Make sure at-least one of the GPIO is defined and that
> 	 * a name is specified for this instance
> 	 */
> 	if ((!dev->device_wakeup && !dev->shutdown) || !dev->name) {
> 		dev_err(&pdev->dev, "invalid platform data\n");
> 		return -EINVAL;
> 	}
> 
> However the same commit added a call to bcm_gpio_set_power() to the
> ->probe hook, which unconditionally accesses *both* GPIOs.  Luckily,
> the resulting NULL pointer deref was never reported, suggesting there's
> no machine where either GPIO is missing.
> 
> Commit 8a92056837fd ("Bluetooth: hci_bcm: Add (runtime)pm support to the
> serdev driver") removed the check whether at least one of the GPIOs is
> present without specifying a reason.
> 
> Because commit 62aaefa7d038 ("Bluetooth: hci_bcm: improve use of gpios
> API") refactored the driver to use devm_gpiod_get_optional() instead of
> devm_gpiod_get(), one is now tempted to believe that the driver doesn't
> require *any* of the two GPIOs.
> 
> Which is wrong, the driver still requires both GPIOs to avoid a NULL
> pointer deref.  To this end, establish the status quo ante and request
> the GPIOs with devm_gpiod_get() again.  Bail out of ->probe if either
> of them is missing.
> 
> Oddly enough, whereas bcm_gpio_set_power() accesses the device wake pin
> unconditionally, bcm_suspend_device() and bcm_resume_device() do check
> for its presence before accessing it.  Those checks are superfluous,
> so remove them.
> 
> Cc: Frédéric Danis <frederic.danis.oss@...il.com>
> Cc: Loic Poulain <loic.poulain@...aro.org>
> Cc: Hans de Goede <hdegoede@...hat.com>
> Cc: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> Cc: Linus Walleij <linus.walleij@...aro.org>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Signed-off-by: Lukas Wunner <lukas@...ner.de>
> Signed-off-by: Marcel Holtmann <marcel@...tmann.org>
> Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
> ---
>  drivers/bluetooth/hci_bcm.c | 24 +++++++++---------------
>  1 file changed, 9 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/bluetooth/hci_bcm.c b/drivers/bluetooth/hci_bcm.c
> index 707c2d1b84c7..b8eeac4e6f35 100644
> --- a/drivers/bluetooth/hci_bcm.c
> +++ b/drivers/bluetooth/hci_bcm.c
> @@ -577,11 +577,9 @@ static int bcm_suspend_device(struct device *dev)
>  	}
>  
>  	/* Suspend the device */
> -	if (bdev->device_wakeup) {
> -		gpiod_set_value(bdev->device_wakeup, false);
> -		bt_dev_dbg(bdev, "suspend, delaying 15 ms");
> -		mdelay(15);
> -	}
> +	gpiod_set_value(bdev->device_wakeup, false);
> +	bt_dev_dbg(bdev, "suspend, delaying 15 ms");
> +	mdelay(15);
>  
>  	return 0;
>  }
> @@ -592,11 +590,9 @@ static int bcm_resume_device(struct device *dev)
>  
>  	bt_dev_dbg(bdev, "");
>  
> -	if (bdev->device_wakeup) {
> -		gpiod_set_value(bdev->device_wakeup, true);
> -		bt_dev_dbg(bdev, "resume, delaying 15 ms");
> -		mdelay(15);
> -	}
> +	gpiod_set_value(bdev->device_wakeup, true);
> +	bt_dev_dbg(bdev, "resume, delaying 15 ms");
> +	mdelay(15);
>  
>  	/* When this executes, the device has woken up already */
>  	if (bdev->is_suspended && bdev->hu) {
> @@ -779,14 +775,12 @@ static int bcm_get_resources(struct bcm_device *dev)
>  
>  	dev->clk = devm_clk_get(dev->dev, NULL);
>  
> -	dev->device_wakeup = devm_gpiod_get_optional(dev->dev,
> -						     "device-wakeup",
> -						     GPIOD_OUT_LOW);
> +	dev->device_wakeup = devm_gpiod_get(dev->dev, "device-wakeup",
> +					    GPIOD_OUT_LOW);
>  	if (IS_ERR(dev->device_wakeup))
>  		return PTR_ERR(dev->device_wakeup);
>  
> -	dev->shutdown = devm_gpiod_get_optional(dev->dev, "shutdown",
> -						GPIOD_OUT_LOW);
> +	dev->shutdown = devm_gpiod_get(dev->dev, "shutdown", GPIOD_OUT_LOW);
>  	if (IS_ERR(dev->shutdown))
>  		return PTR_ERR(dev->shutdown);
>  
> -- 
> 2.14.1