linux-kernel - Re: [PATCH v2 0/2] Introduce BACKGROUND

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Message-ID: <0e7d78e0-36ee-4115-b224-dbf4bda87ede@collabora.com>
Date: Mon, 10 Nov 2025 16:22:21 +0200
From: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: 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>,
 Robert Mader <robert.mader@...labora.com>, 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 v2 0/2] Introduce BACKGROUND_COLOR DRM CRTC property

On 10/13/25 11:55 PM, Dmitry Baryshkov wrote:
> On Mon, Oct 13, 2025 at 09:27:17PM +0300, 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.
> 
> 
> Please provide IGT tests. I'd at least check that using the
> BACKGROUND_COLOR results in the same CRC as then one when there is a
> plane covering the whole screen.

Done:

https://lore.kernel.org/all/20251110-crtc-bgcolor-v1-1-28669b692970@collabora.com/

> Additional note. I see a value in having the CRTC property for the
> background colour. However it might be more flexible to reuse old
> proposal for solid fill planes ([1]) and instead implement the lowest
> Z-order plane supporting only solid fill colour as an image source.

Thanks for pointing this out.  Will keep it in mind as for now there is no
(immediate) plan to consider the alternative(s).