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

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Message-ID: <7a6eba4c-0d24-47c2-92ad-f63116d45a69@redhat.com>
Date: Fri, 3 Oct 2025 17:15:09 +0200
From: Jocelyn Falempe <jfalempe@...hat.com>
To: Francesco Valla <francesco@...la.it>,
 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>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/draw: fix color truncation in drm_draw_fill24

On 10/3/25 16:41, Francesco Valla wrote:
> 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.

Thanks, I was wondering if this 24bit code would see a real usage, so it 
looks like this is still a thing in 2025.

Best regards,

-- 

Jocelyn

> 
> Best regards,
> 
> Francesco
> 
> 
> 
> 
> 
>