linux-kernel - Re: [PATCH 0/2] Introduce BACKGROUND

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Message-ID: <fc9baa6d-ed38-478b-9338-8a76986639da@collabora.com>
Date: Tue, 2 Sep 2025 19:04:50 +0300
From: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To: Raphael Gallais-Pou <raphael.gallais-pou@...s.st.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>,
 Sandy Huang <hjc@...k-chips.com>, Heiko Stübner
 <heiko@...ech.de>, Andy Yan <andy.yan@...k-chips.com>
Cc: kernel@...labora.com, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, Matt Roper <matthew.d.roper@...el.com>
Subject: Re: [PATCH 0/2] Introduce BACKGROUND_COLOR DRM CRTC property

Hi Raphael,

On 9/2/25 4:19 PM, Raphael Gallais-Pou wrote:
> 
> 
> On 9/2/25 11:27, Cristian Ciocaltea wrote:
>> Some display controllers can be hardware-configured to present non-black
>> colors for pixels which are not covered by any plane (or are exposed
>> through transparent regions of higher planes).
>>
>> The first patch of the series introduces the BACKGROUND_COLOR DRM
>> property that can be attached to a CRTC via a dedicated helper function.
>> A 64-bit ARGB color value format is also defined and can be manipulated
>> with the help of a few utility macros.
> 
> Hi Cristian,
> 
> Thanks for this work ! :)
> 
> FWIW I sent a series also based on Matt's work four years ago:
> https://lore.kernel.org/dri-devel/20210707084557.22443-2-raphael.gallais-pou@foss.st.com/
> 
> IIRC at the time there was some questions around the pixel format used for the
> property, and non-opaque color vs alpha pre-multiplication.
> Mind that on STM32MP platforms alpha channel for the background color is not
> supported.
> 
> Hope the thread can bring some insights.

Thanks for pointing this out, I will consider it for v2.

Regards,
Cristian