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Date:   Fri, 11 Feb 2022 13:11:25 +0100
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Subject: Re: [PATCH v4 1/6] drm/format-helper: Add
 drm_fb_xrgb8888_to_gray8_line()
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To:     Jani Nikula <jani.nikula@linux.intel.com>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     linux-fbdev@vger.kernel.org, David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= <noralf@tronnes.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Maxime Ripard <maxime@cerno.tech>,
        Sam Ravnborg <sam@ravnborg.org>
References: <20220211091927.2988283-1-javierm@redhat.com>
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From:   Javier Martinez Canillas <javierm@redhat.com>
In-Reply-To: <87pmnt7gm3.fsf@intel.com>
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Hello Jani,

On 2/11/22 13:05, Jani Nikula wrote:

[snip]

>>>> I don't see why a while loop would be an improvement here TBH.
>>>
>>> Less letters to parse when reading the code.
>>
>> It's a simple refactoring of code that has worked well so far. Let's 
>> leave it as-is for now.
> 
> IMO *always* prefer a for loop over while or do-while.
> 
> The for (i = 0; i < N; i++) is such a strong paradigm in C. You
> instantly know how many times you're going to loop, at a glance. Not so
> with with the alternatives, which should be used sparingly.
> 
> And yes, the do-while suggested above is buggy, and you actually need to
> stop and think to see why.
>

Absolutely agree.

These format conversion helpers are not trivial to read and understand (at
least for me). In my opinion the code should be written in a way that ease
readability and make as robust and less error prone as possible.
 
> 
> BR,
> Jani.
Best regards,
-- 
Javier Martinez Canillas
Linux Engineering
Red Hat