linux-kernel - Re: [PATCH v3 1/2] i2c: Add driver for Cadence I2C controller

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Date:	Thu, 03 Apr 2014 09:25:47 +0200
From:	Michal Simek <monstr@...str.eu>
To:	Wolfram Sang <wsa@...-dreams.de>
CC:	Soren Brinkmann <soren.brinkmann@...inx.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Rob Landley <rob@...dley.net>,
	Russell King <linux@....linux.org.uk>,
	Michal Simek <michal.simek@...inx.com>,
	Grant Likely <grant.likely@...aro.org>,
	Mike Looijmans <mike.looijmans@...ic.nl>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-doc@...r.kernel.org, devicetree@...r.kernel.org,
	linux-i2c@...r.kernel.org, Harini Katakam <harinik@...inx.com>
Subject: Re: [PATCH v3 1/2] i2c: Add driver for Cadence I2C controller

On 04/03/2014 09:10 AM, Wolfram Sang wrote:
> 
> Please don't quote large parts of the message f you are not referring to
> it.

Normally I do it. Forgot sorry.

>>> +#ifdef CONFIG_PM_SLEEP
>>> +/**
>>> + * cdns_i2c_suspend - Suspend method for the driver
>>> + * @_dev:	Address of the platform_device structure
>>> + * Return: 0 always
>>> + *
>>> + * Put the driver into low power mode.
>>> + */
>>> +static int cdns_i2c_suspend(struct device *_dev)
>>> +{
>>> +	struct platform_device *pdev = container_of(_dev,
>>> +			struct platform_device, dev);
>>> +	struct cdns_i2c *xi2c = platform_get_drvdata(pdev);
>>> +
>>> +	clk_disable(xi2c->clk);
>>> +	xi2c->suspended = 1;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +/**
>>> + * cdns_i2c_resume - Resume from suspend
>>> + * @_dev:	Address of the platform_device structure
>>> + * Return: 0 on success and error value on error
>>> + *
>>> + * Resume operation after suspend.
>>> + */
>>> +static int cdns_i2c_resume(struct device *_dev)
>>> +{
>>> +	struct platform_device *pdev = container_of(_dev,
>>> +			struct platform_device, dev);
>>> +	struct cdns_i2c *xi2c = platform_get_drvdata(pdev);
>>> +	int ret;
>>> +
>>> +	ret = clk_enable(xi2c->clk);
>>> +	if (ret) {
>>> +		dev_err(_dev, "Cannot enable clock.\n");
>>> +		return ret;
>>> +	}
>>> +
>>> +	xi2c->suspended = 0;
>>> +
>>> +	return 0;
>>> +}
>>> +#endif
>>
>> Can you also please remove this #ifdef and use __maybe_used
>> instead? Better not to have any ifdef in the code.
> 
> Is this a new pattern? For PM_SLEEP, #ifdef seems to be quite common.

The first suggestion to do it came from CAN maintainer.
It is valid in general for ifdef.
I have checked all our drivers and we are changing them to use __maybe_used
because then we can easily find out if there is any problem
when function prototype has changed.

Thanks,
Michal


-- 
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform



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