linux-kernel - Re: [PATCH] fbdev: auo_k190x: avoid unused function warnings

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Message-ID: <5665B1CD.2020206@ti.com>
Date:	Mon, 7 Dec 2015 18:20:29 +0200
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	Arnd Bergmann <arnd@...db.de>
CC:	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	<linux-fbdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] fbdev: auo_k190x: avoid unused function warnings



On 07/12/15 18:16, Arnd Bergmann wrote:
> On Monday 07 December 2015 18:10:04 Tomi Valkeinen wrote:
>> On 20/11/15 23:47, Arnd Bergmann wrote:
>>> The auo_k190x framebuffer driver encloses the power-management
>>> functions in #ifdef CONFIG_PM, but the auok190x_suspend/resume
>>> functions are only really used when CONFIG_PM_SLEEP is also
>>> set, as a frequent gcc warning shows:
>>>
>>> drivers/video/fbdev/auo_k190x.c:859:12: warning: 'auok190x_suspend' defined but not used
>>> drivers/video/fbdev/auo_k190x.c:899:12: warning: 'auok190x_resume' defined but not used
>>>
>>> This changes the driver to remove the #ifdef and instead mark
>>> the functions as __maybe_unused, which is a nicer anyway, as it
>>> provides build testing for all the code in all configurations
>>> and is harder to get wrong.
>>
>> Applied for 4.5.
>>
>> Btw, do you know if the linker will optimize the __maybe_unused funcs
>> away if they are not used? I presume so.
>>
> 
> The compiler does it correctly when built with -O1 or higher (we don't
> support -O0), and the linker is not involved here.

Ah, right, they were static. I was thinking of non-static functions. But
__maybe_unused is not even needed for non-static, so... Never mind =)

 Tomi


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