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

Jani Nikula
2015-11-06T13:13:13Z

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