linux-kernel - Re: [PATCH 2/3] watchdog: bcm2835: Add poweroff code for the Raspberry Pi

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Message-ID: <557ACE07.3040104@roeck-us.net>
Date:	Fri, 12 Jun 2015 05:18:15 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Stefan Wahren <info@...egoodbye.de>,
	Noralf Trønnes <noralf@...nnes.org>,
	linux-arm-kernel@...ts.infradead.org
CC:	devicetree@...r.kernel.org, linux-watchdog@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/3] watchdog: bcm2835: Add poweroff code for the Raspberry
 Pi

On 06/12/2015 04:26 AM, Stefan Wahren wrote:
> Hi Noralf,
>
> Am 09.06.2015 um 12:21 schrieb Noralf Trønnes:
>> This adds a new poweroff function to the watchdog driver for the
>> Raspberry Pi. Currently poweroff/halt results in a reboot.
>>
>> [...]
>>
>> +static void rpi_power_off(void)
>> +{
>> +    struct device_node *np =
>> +        of_find_compatible_node(NULL, NULL, "brcm,raspberrypi-pm-wdt");
>> +    struct platform_device *pdev = of_find_device_by_node(np);
>> +    struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
>> +    u32 val;
>> +
>> +    val = readl_relaxed(wdt->base + PM_RSTS);
>
> do you think it's safe here to assume wdt could never be NULL?
>

If the call is made, the driver must be instantiated. We can therefore assume
that neither np, pdev, nor wdt is NULL. If one of those is NULL, it would be
a bug, which should not be ignored.

Guenter

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