linux-kernel - Re: [PATCH] drm/draw: fix color truncation in drm_draw

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Message-ID: <3881844.vuYhMxLoTh@fedora-2.fritz.box>
Date: Fri, 03 Oct 2025 16:41:54 +0200
From: Francesco Valla <francesco@...la.it>
To: Javier Martinez Canillas <javierm@...hat.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Jocelyn Falempe <jfalempe@...hat.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/draw: fix color truncation in drm_draw_fill24

Hi Jocelyn,

On Friday, 3 October 2025 at 14:48:03 Jocelyn Falempe <jfalempe@...hat.com> wrote:
> On 10/3/25 12:33, Francesco Valla wrote:
> > The color parameter passed to drm_draw_fill24() was truncated to 16
> > bits, leading to an incorrect color drawn to the target iosys_map.
> > Fix this behavior, widening the parameter to 32 bits.
> > 
> Oh, you're right, my mistake.
> Did you find this by using a 24bit hardware, or by looking at the code?
> 
> Reviewed-by: Jocelyn Falempe <jfalempe@...hat.com>
> 
> Best regards,
> 

I am working on a graphical splash DRM client (which I hope I'll be
able to post soon) and testing it on a Beagleplay - which is
RG24-capable - I started to see a strange behavior with non-black
colors. After some investigation I found the cuplrit, and strangely
enough it wasn't me this time.

Best regards,

Francesco