On Tue, Oct 13, 2026 at 11:32:36AM +0200, Màxim Pedraza Padilla wrote:
> Products built on the same board often differ only in branding. On UEFI
> systems the firmware hands the operating system its boot logo through
> the ACPI BGRT; a device tree system has no such table, so today the logo
> is built into the kernel, and each product needs its own kernel image.
> With U-Boot's Falcon mode the device tree is the only thing that reaches
> the kernel, so it is also the only place the logo can come from.
>
> Add a "boot-logo" node under /chosen. The node lives there because a
> logo is configuration handed over by firmware rather than a description
> of the hardware, as simple-framebuffer nodes already are.
>
> The image is a BMP with 24 bits per pixel and no compression, the
> format of the BGRT image, so that one file serves the firmware splash,
> a BMP loaded as firmware and this node alike. It is carried either in
> an "image" property, which dtc fills in from the file with /incbin/, or
> in a reserved memory region the bootloader loaded it into, named by
> "memory-region". Exactly one of the two must be present.
>
> "logo-position" takes -1 on an axis to mean centre on that axis, which
> is the only way to say it when the device tree does not know the image
> size, and "logo-offset" is added afterwards. "rotation" counts degrees
> counter clockwise, as for panels, and turns the image rather than the
> screen, so position and offset stay in screen pixels. The optional
> "background-color" goes with the image, since a logo designed for one
> background looks wrong on another.
>
> Assisted-by: Claude:claude-opus-5-5
> Signed-off-by: Màxim Pedraza Padilla <[email protected]>
> ---
> .../bindings/display/boot-logo.yaml | 151 ++++++++++++++++++
> MAINTAINERS | 1 +
> 2 files changed, 152 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/display/boot-logo.yaml
>
> diff --git a/Documentation/devicetree/bindings/display/boot-logo.yaml
> b/Documentation/devicetree/bindings/display/boot-logo.yaml
> new file mode 100644
> index 000000000000..bf4121f24f1b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/boot-logo.yaml
> @@ -0,0 +1,151 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/boot-logo.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Boot logo supplied by the device tree
> +
> +maintainers:
> + - Francesco Valla <[email protected]>
> + - Màxim Pedraza Padilla <[email protected]>
> +
> +description: |
> + An image for the operating system to show on the display while it boots,
> + handed over by the firmware together with where and how to show it.
> +
> + Products built on the same board often differ only in branding. Carrying
> + the logo in the device tree lets a single kernel image serve all of them,
> + each booting with its own device tree, and it works where the device tree
> + is the only thing that reaches the kernel, as with U-Boot's Falcon mode.
> + It plays the part the ACPI BGRT plays on UEFI systems.
> +
> + Since a logo is configuration rather than a description of the hardware,
> + the node lives under /chosen, next to the other things firmware hands to
> + the operating system.
> +
> + The image is a BMP file with a 40 byte BITMAPINFOHEADER, 24 bits per pixel
> + and no compression, the format of the BGRT image. It is carried either in
> + the node itself or in a reserved memory region the bootloader loaded it
> + into, never both.
> +
> +properties:
> + $nodename:
> + const: logo
> +
> + compatible:
> + const: boot-logo
> +
> + image:
A bit too generic for me. How about logo-image for consistency.
> + $ref: /schemas/types.yaml#/definitions/uint8-array
> + description:
> + The BMP file itself, byte for byte, which dtc can fill in from the file
> + with /incbin/. The device tree stays in memory for as long as the
> + system runs, so this is meant for small images; larger ones belong in
> + a reserved memory region.
> +
> + memory-region:
> + maxItems: 1
> + description: |
> + Reserved memory region the bootloader loaded the BMP file into,
> starting
> + at the beginning of the region. The BMP header says how much of the
> + region is image.
> +
> + This keeps the image out of the device tree, so that it can be changed
> + without rebuilding the device tree, for instance by loading it from a
> + partition of its own that userspace can update.
> +
> + Memory keeps its contents across a reset, and may even across a short
> + power cycle, and the operating system cannot tell a stale image from a
> + fresh one. A bootloader that loads no image into the region therefore
> + disables the node (status = "disabled") or removes it.
> +
> + logo-position:
> + $ref: /schemas/types.yaml#/definitions/int32-array
> + description:
> + X and Y coordinates, in screen pixels, of the top left corner of the
> + image once it has been rotated. A value of -1 on an axis centres the
> + image on that axis instead, which is the only way to say it when the
> + device tree does not know the image size, as with a memory region.
> + Defaults to centring on both axes.
> + items:
> + - description: X coordinate, or -1 to centre horizontally
> + minimum: -1
> + maximum: 65535
> + - description: Y coordinate, or -1 to centre vertically
> + minimum: -1
> + maximum: 65535
> +
> + logo-offset:
> + $ref: /schemas/types.yaml#/definitions/int32-array
> + description:
> + X and Y displacement, in screen pixels, applied after the image has
> been
> + placed. Mostly useful together with a centred axis, to land the image
> + somewhere other than the middle of a panel whose visible area is not
> + the middle of the mode.
> + items:
> + - description: X displacement
> + minimum: -65535
> + maximum: 65535
> + - description: Y displacement
> + minimum: -65535
> + maximum: 65535
> +
> + rotation:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + description:
> + Rotation applied to the image before it is shown, in degrees counter
> + clockwise, as for the rotation property of panels. It turns the image
> + and not the screen, so a quarter turn swaps how much room the image
> + takes up, but logo-position and logo-offset stay in screen pixels
> + either way.
> + enum: [0, 90, 180, 270]
> + default: 0
This property is already defined in panel-common.yaml, so you need a ref
to it. You probably don't want everything from there, so just 'rotation:
true' here. Though keeping the description here is probably worthwhile.
> +
> + background-color:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + description:
> + Colour of the rest of the screen, as 0xRRGGBB. When absent, the
> + operating system uses its own default.
> + maximum: 0xffffff
> +
> +required:
> + - compatible
> +
> +# The image lives either in the node or in a reserved memory region,
> +# never both and never neither.
> +oneOf:
> + - required:
> + - image
> + - required:
> + - memory-region
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + // A 2x1 image, red and blue, centred and 120 pixels below the middle
> + / {
> + compatible = "foo";
> + model = "foo";
> + #address-cells = <1>;
> + #size-cells = <1>;
> +
> + chosen {
> + logo {
> + compatible = "boot-logo";
> + /* Normally: image = /incbin/("logo.bmp"); */
> + image = /bits/ 8 <0x42 0x4d 0x3e 0x00 0x00 0x00 0x00 0x00
> + 0x00 0x00 0x36 0x00 0x00 0x00 0x28 0x00
> + 0x00 0x00 0x02 0x00 0x00 0x00 0x01 0x00
> + 0x00 0x00 0x01 0x00 0x18 0x00 0x00 0x00
> + 0x00 0x00 0x08 0x00 0x00 0x00 0x13 0x0b
> + 0x00 0x00 0x13 0x0b 0x00 0x00 0x00 0x00
> + 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
> + 0xff 0xff 0x00 0x00 0x00 0x00>;
> + logo-position = <(-1) (-1)>;
> + logo-offset = <0 120>;
> + background-color = <0x1e1e28>;
> + };
> + };
> + };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 321ecb9f5b5b..0d1decaedde0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9174,6 +9174,7 @@ M: Màxim Pedraza Padilla <[email protected]>
> L: [email protected]
> S: Maintained
> T: git https://gitlab.freedesktop.org/drm/misc/kernel.git
> +F: Documentation/devicetree/bindings/display/boot-logo.yaml
> F: drivers/gpu/drm/clients/drm_splash.c
>
> DRM TTM SUBSYSTEM
> --
> 2.39.5
>
