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

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Message-ID: <x33zabb5un2boben6r4qp3vvrgca5s37gmseespdwwbajumdxx@mcxe6or5p63m>
Date: Mon, 13 Oct 2025 23:55:39 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Cristian Ciocaltea <cristian.ciocaltea@...labora.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 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.

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.

[1] https://lore.kernel.org/dri-devel/20231027-solid-fill-v7-0-780188bfa7b2@quicinc.com/

-- 
With best wishes
Dmitry