Re: GPU-DRM-i915: Delete an unnecessary check before the function call "pwm_put"

From	Jani Nikula <jani.nikula@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: GPU-DRM-i915: Delete an unnecessary check before the function call "pwm_put"
Date	2015-11-06 14:20 +0100
Message-ID	<qrP5U-4Zf-17@gated-at.bofh.it> (permalink)
References	(15 earlier) <mSsDN-4wa-65@gated-at.bofh.it> <mSsDN-4wa-33@gated-at.bofh.it> <qrOCS-4yt-11@gated-at.bofh.it> <qrOCS-4yt-9@gated-at.bofh.it> <qrOMx-4BZ-11@gated-at.bofh.it>
Organization	Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo

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On Fri, 06 Nov 2015, SF Markus Elfring <elfring@users.sourceforge.net> wrote:
>>> The pwm_put() function tests whether its argument is NULL and then
>>> returns immediately. Thus the test around the call is not needed.
>> 
>> The compiler doesn't need it, but IMO it's useful documentation for humans.
>
> How do you think about to extend the explicit documentation for
> the affected parameters in the Linux programming interfaces?

The question is, while reading intel_panel.c, which one conveys the
reader better the idea that panel->backlight.pwm may be NULL for some
connectors:

a)	if (panel->backlight.pwm)
		pwm_put(panel->backlight.pwm);
	
b)	pwm_put(panel->backlight.pwm);

No amount of documentation in pwm_put() kernel-doc is going to help with
that. In most cases, panel->backlight.pwm is in fact NULL. IMO
unconditionally calling pwm_put() on it gives the reader the wrong idea.

Others may disagree.

BR,
Jani.


-- 
Jani Nikula, Intel Open Source Technology Center
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Re: [PATCH] GPU-DRM-i915: Delete an unnecessary check before the function call "pwm_put" Jani Nikula <jani.nikula@linux.intel.com> - 2015-11-06 13:50 +0100
  Re: GPU-DRM-i915: Delete an unnecessary check before the function  call "pwm_put" SF Markus Elfring <elfring@users.sourceforge.net> - 2015-11-06 14:00 +0100
    Re: GPU-DRM-i915: Delete an unnecessary check before the function call "pwm_put" Jani Nikula <jani.nikula@linux.intel.com> - 2015-11-06 14:20 +0100

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