From: linux@roeck-us•net (Guenter Roeck)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 2/2] ARM: BCM2835: Move the restart/power_off handling to the WDT driver.
Date: Mon, 27 Apr 2015 05:44:14 -0700 [thread overview]
Message-ID: <553E2F1E.5070909@roeck-us.net> (raw)
In-Reply-To: <2979294.WseZH0BUZW@wuerfel>
On 04/27/2015 02:18 AM, Arnd Bergmann wrote:
> On Sunday 26 April 2015 08:35:57 Guenter Roeck wrote:
>> On 04/25/2015 01:11 PM, Arnd Bergmann wrote:
>>> On Friday 24 April 2015 12:08:54 Eric Anholt wrote:
>>>> +/*
>>>> + * We can't really power off, but if we do the normal reset scheme, and
>>>> + * indicate to bootcode.bin not to reboot, then most of the chip will be
>>>> + * powered off.
>>>> + */
>>>> +static void bcm2835_power_off(void)
>>>> +{
>>>> + struct device_node *np =
>>>> + of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
>>>> + struct platform_device *pdev = of_find_device_by_node(np);
>>>> + struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
>>>> + u32 val;
>>>> +
>>>
>>> Instead of doing the lookup again here, I'd suggest using a static variable
>>> in the driver to store the device pointer for the device used on power_off.
>>>
>>> Make sure that the device remove callback assigns it back to NULL though
>>> and that the function checks for NULL pointer.
>>>
>>
>> Why would that be needed ?
>
> devices can be unbound from drivers through sysfs, or using dynamic DT
> updates. If one does that, the watchdog driver will correctly destroy
> all information it has about the device, so if the power_off function
> still uses that pointer, it will crash.
>
Without calling its remove function ? That sounds odd. Lots of drivers
would break if that was really the case.
Guenter
next prev parent reply other threads:[~2015-04-27 12:44 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-24 19:08 [PATCH 1/2] ARM: BCM2835: Drop the init_irq() hook Eric Anholt
2015-04-24 19:08 ` [PATCH 2/2] ARM: BCM2835: Move the restart/power_off handling to the WDT driver Eric Anholt
2015-04-24 19:32 ` Pranith Kumar
2015-04-25 4:39 ` Stephen Warren
2015-04-25 20:11 ` Arnd Bergmann
2015-04-26 15:35 ` Guenter Roeck
2015-04-27 9:18 ` Arnd Bergmann
2015-04-27 12:44 ` Guenter Roeck [this message]
2015-04-27 12:48 ` Arnd Bergmann
2015-04-27 13:28 ` Guenter Roeck
2015-04-27 13:32 ` Arnd Bergmann
2015-04-27 12:58 ` Lubomir Rintel
2015-04-27 16:04 ` Guenter Roeck
2015-04-27 16:05 ` Guenter Roeck
2015-04-27 23:12 ` Eric Anholt
2015-04-28 1:39 ` Guenter Roeck
2015-04-28 9:22 ` Lee Jones
2015-04-28 19:38 ` Eric Anholt
2015-04-27 18:28 ` Lee Jones
2015-04-29 2:35 ` [2/2] " Guenter Roeck
2015-04-29 6:45 ` [PATCH 2/2] " Lee Jones
2015-04-27 18:29 ` [PATCH 1/2] ARM: BCM2835: Drop the init_irq() hook Lee Jones
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