netdev - Re: [PATCH v4] can: Convert to runtime

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Message-ID: <54AD5F13.1020107@pengutronix.de>
Date:	Wed, 07 Jan 2015 17:30:11 +0100
From:	Marc Kleine-Budde <mkl@...gutronix.de>
To:	Sören Brinkmann <soren.brinkmann@...inx.com>
CC:	Kedareswara rao Appana <appana.durga.rao@...inx.com>,
	wg@...ndegger.com, michal.simek@...inx.com,
	grant.likely@...aro.org, linux-can@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Kedareswara rao Appana <appanad@...inx.com>
Subject: Re: [PATCH v4] can: Convert to runtime_pm

On 01/07/2015 04:58 PM, Sören Brinkmann wrote:
>> I think you have to convert the _remove() function, too. Have a look at
>> the gpio-zynq.c driver:
>>
>>> static int zynq_gpio_remove(struct platform_device *pdev)
>>> {
>>> 	struct zynq_gpio *gpio = platform_get_drvdata(pdev);
>>>
>>> 	pm_runtime_get_sync(&pdev->dev);
>>
>> However I don't understand why the get_sync() is here. Maybe Sören can help?
> 
> IIRC, the concern was that the remove function may be called while the device is
> runtime suspended. Hence the remove function needs to resume the device since the
> remove function may access the HW.

What about the corresponding runtime_put()? Would some counter be
unbalanced upon device removal?

Without having tested it, unloading and loading, i.e. reloading a CAN
driver is easier than reloading the gpio driver on an average embedded
system. Kedareswara please test your driver with something like:
modprobe; ifconfig up; cansend; ifconfig down; rmmod in a loop.

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
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