linux-kernel - Re: [PATCH 1/5] drm/format-helper: Rename drm_fb_xrgb8888_to_mono

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Date:   Tue, 15 Mar 2022 12:59:56 +0100
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Noralf Trønnes <noralf@...nnes.org>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] drm/format-helper: Rename
 drm_fb_xrgb8888_to_mono_reversed()

Hello Geert,

Thanks for your patch.

On 3/15/22 12:07, Geert Uytterhoeven wrote:
> There is no "reversed" handling in drm_fb_xrgb8888_to_mono_reversed():
> the function just converts from color to grayscale, and reduces the
> number of grayscale levels from 256 to 2 (i.e. brightness 0-127 is
> mapped to 0, 128-255 to 1).  All "reversed" handling is done in the
> repaper driver, where this function originated.
> 
> Hence make this clear by renaming drm_fb_xrgb8888_to_mono_reversed() to
> drm_fb_xrgb8888_to_mono(), and documenting the black/white pixel
> mapping.
> 
> Fixes: bcf8b616deb87941 ("drm/format-helper: Add drm_fb_xrgb8888_to_mono_reversed()")
> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> ---
As you mentioned the function originally came from the repaper driver
(that uses white-on-black) and I wrongly assumed that the destination
buffer for the OLED panels were also monochrome reversed.

Acked-by: Javier Martinez Canillas <javierm@...hat.com>

-- 
Best regards,

Javier Martinez Canillas
Linux Engineering
Red Hat