linux-loongson/Documentation/devicetree/bindings/display/mediatek/mediatek,gamma.yaml
AngeloGioacchino Del Regno 2b6433f30b dt-bindings: display: mediatek: Add OF graph support for board path
The display IPs in MediaTek SoCs support being interconnected with
different instances of DDP IPs (for example, merge0 or merge1) and/or
with different DDP IPs (for example, rdma can be connected with either
color, dpi, dsi, merge, etc), forming a full Display Data Path that
ends with an actual display.

The final display pipeline is effectively board specific, as it does
depend on the display that is attached to it, and eventually on the
sensors supported by the board (for example, Adaptive Ambient Light
would need an Ambient Light Sensor, otherwise it's pointless!), other
than the output type.

Add support for OF graphs to most of the MediaTek DDP (display) bindings
to add flexibility to build custom hardware paths, hence enabling board
specific configuration of the display pipeline and allowing to finally
migrate away from using hardcoded paths.

Please note that - while this commit retains retro-compatibility with
old device trees - it will break the ABI for mediatek,dsi and for
mediatek,dpi for the sake of consistency between the `ports` in all
MediaTek DRM drivers versus DRM bridge drivers as in the previous
binding, MediaTek was using `port` (implicitly, port@0) as an OUTPUT,
while now the first port is an INPUT, and the second one is an OUTPUT,
which is consistent with other DRM drivers which can be chained to
drm/mediatek.

As for maintainability concerns, I am aware that the old device tree
will not be actively tested anymore, but retrocompatibility breakages
will *not* be more likely to happen in the future because any addition
to the graph (new drivers) will be done only for features present on
newer SoCs, keeping the old ones (and their default pipeline) untouched.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Tested-by: Alexandre Mergnat <amergnat@baylibre.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Tested-by: Michael Walle <mwalle@kernel.org> # on kontron-sbc-i1200
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20241017103809.156056-2-angelogioacchino.delregno@collabora.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
2024-10-21 12:39:14 +00:00

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# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/display/mediatek/mediatek,gamma.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: Mediatek display gamma correction
maintainers:
- Chun-Kuang Hu <chunkuang.hu@kernel.org>
- Philipp Zabel <p.zabel@pengutronix.de>
description: |
Mediatek display gamma correction, namely GAMMA, provides a nonlinear
operation used to adjust luminance in display system.
GAMMA device node must be siblings to the central MMSYS_CONFIG node.
For a description of the MMSYS_CONFIG binding, see
Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml
for details.
properties:
compatible:
oneOf:
- enum:
- mediatek,mt8173-disp-gamma
- mediatek,mt8183-disp-gamma
- mediatek,mt8195-disp-gamma
- items:
- enum:
- mediatek,mt6795-disp-gamma
- const: mediatek,mt8173-disp-gamma
- items:
- enum:
- mediatek,mt8186-disp-gamma
- mediatek,mt8188-disp-gamma
- mediatek,mt8192-disp-gamma
- mediatek,mt8195-disp-gamma
- mediatek,mt8365-disp-gamma
- const: mediatek,mt8183-disp-gamma
- items:
- enum:
- mediatek,mt8188-disp-gamma
- const: mediatek,mt8195-disp-gamma
reg:
maxItems: 1
interrupts:
maxItems: 1
power-domains:
description: A phandle and PM domain specifier as defined by bindings of
the power controller specified by phandle. See
Documentation/devicetree/bindings/power/power-domain.yaml for details.
clocks:
items:
- description: GAMMA Clock
mediatek,gce-client-reg:
description: The register of client driver can be configured by gce with
4 arguments defined in this property, such as phandle of gce, subsys id,
register offset and size. Each GCE subsys id is mapping to a client
defined in the header include/dt-bindings/gce/<chip>-gce.h.
$ref: /schemas/types.yaml#/definitions/phandle-array
maxItems: 1
ports:
$ref: /schemas/graph.yaml#/properties/ports
properties:
port@0:
$ref: /schemas/graph.yaml#/properties/port
description: GAMMA input, usually from one of the AAL blocks.
port@1:
$ref: /schemas/graph.yaml#/properties/port
description:
GAMMA output to the input of the next desired component in the
display pipeline, for example one of the available DITHER or
POSTMASK blocks.
required:
- port@0
- port@1
required:
- compatible
- reg
- interrupts
- power-domains
- clocks
additionalProperties: false
examples:
- |
#include <dt-bindings/interrupt-controller/arm-gic.h>
#include <dt-bindings/clock/mt8173-clk.h>
#include <dt-bindings/power/mt8173-power.h>
#include <dt-bindings/gce/mt8173-gce.h>
soc {
#address-cells = <2>;
#size-cells = <2>;
gamma@14016000 {
compatible = "mediatek,mt8173-disp-gamma";
reg = <0 0x14016000 0 0x1000>;
interrupts = <GIC_SPI 190 IRQ_TYPE_LEVEL_LOW>;
power-domains = <&scpsys MT8173_POWER_DOMAIN_MM>;
clocks = <&mmsys CLK_MM_DISP_GAMMA>;
mediatek,gce-client-reg = <&gce SUBSYS_1401XXXX 0x6000 0x1000>;
};
};