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90090f49f1
The OLDI transmitters (TXes) do not have registers of their own, and are
dependent on the source video-ports (VPs) from the DSS to provide
configuration data. This hardware doesn't directly sit on the internal
bus of the SoC, but does so via the DSS. Hence, the OLDI TXes are
supposed to be child nodes under the DSS, and not independent devices.
Two of the OLDI TXes can function in tandem to output dual-link OLDI
output, or cloned single-link outputs. In these cases, one OLDI will be
the primary OLDI, and the other one, a companion. The following diagram
represents such a configuration.
+-----+-----+ +-------+
| | | | |
| | VP1 +----+--->+ OLDI0 | (Primary - may need companion)
| | | | | |
| DSS +-----+ | +-------+
| | | |
| | VP2 | | +-------+
| | | | | |
+-----+-----+ +--->+ OLDI1 | (Companion OLDI)
| |
+-------+
The DSS in AM625 SoC has a configuration like the one above. The AM625
DSS VP1 (port@0) can connect and control 2 OLDI TXes, to use them in
dual-link or cloned single-link OLDI modes. It is only the VP1 that can
connect to either OLDI TXes for the AM625 DSS, and not the VP2.
Alternatively, on some future TI SoCs, along with the above
configuration, the OLDI TX can _also_ connect to separate video sources,
making them work entirely independent of each other. In this case,
neither of the OLDIs are "companion" or "secondary" OLDIs, and nor do
they require one. They both are independent and primary OLDIs. The
following diagram represents such a configuration.
+-----+-----+ +-------+
| | | | |
| | VP1 +--+----------->+ OLDI0 | (Primary - may need companion)
| | | | | |
| +-----+ | +-------+
| | | |
| | VP2 | |
| | | |
| DSS +-----+ | +---+ +-------+
| | | +-->+ M | | |
| | VP3 +----->+ U +--->+ OLDI1 | (Companion or Primary)
| | | | X | | |
| +-----+ +---+ +-------+
| | |
| | VP4 |
| | |
+-----+-----+
Note that depending on the mux configuration, the OLDIs can either be
working together in tandem - sourced by VP1, OR, they could be working
independently sourced by VP1 and VP3 respectively.
The idea is to support all the configurations with this OLDI TX schema.
The OLDI functionality is further supported by a system-control module,
which contains a few registers to control OLDI IO power and other
electrical characteristics of the IO lanes.
Add devicetree binding schema for the OLDI TXes to support various
configurations, and extend their support to the AM625 DSS.
Signed-off-by: Aradhya Bhatia <a-bhatia1@ti.com>
Signed-off-by: Aradhya Bhatia <aradhya.bhatia@linux.dev>
Reviewed-by: "Rob Herring (Arm)" <robh@kernel.org>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://lore.kernel.org/r/20250528122544.817829-3-aradhya.bhatia@linux.dev
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
80 lines
2.3 KiB
YAML
80 lines
2.3 KiB
YAML
# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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%YAML 1.2
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---
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$id: http://devicetree.org/schemas/display/ti/ti,am625-oldi.yaml#
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$schema: http://devicetree.org/meta-schemas/core.yaml#
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title: Texas Instruments AM625 OLDI Transmitter
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maintainers:
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- Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
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- Aradhya Bhatia <aradhya.bhatia@linux.dev>
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description:
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The AM625 TI Keystone OpenLDI transmitter (OLDI TX) supports serialized RGB
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pixel data transmission between host and flat panel display over LVDS (Low
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Voltage Differential Sampling) interface. The OLDI TX consists of 7-to-1 data
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serializers, and 4-data and 1-clock LVDS outputs. It supports the LVDS output
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formats "jeida-18", "jeida-24" and "vesa-18", and can accept 24-bit RGB or
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padded and un-padded 18-bit RGB bus formats as input.
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properties:
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reg:
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maxItems: 1
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clocks:
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maxItems: 1
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description: serial clock input for the OLDI transmitters
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clock-names:
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const: serial
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ti,companion-oldi:
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$ref: /schemas/types.yaml#/definitions/phandle
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description:
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phandle to companion OLDI transmitter. This property is required for both
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the OLDI TXes if they are expected to work either in dual-lvds mode or in
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clone mode. This property should point to the other OLDI TX's phandle.
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ti,secondary-oldi:
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type: boolean
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description:
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Boolean property to mark the OLDI transmitter as the secondary one, when the
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OLDI hardware is expected to run as a companion HW, in cases of dual-lvds
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mode or clone mode. The primary OLDI hardware is responsible for all the
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hardware configuration.
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ti,oldi-io-ctrl:
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$ref: /schemas/types.yaml#/definitions/phandle
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description:
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phandle to syscon device node mapping OLDI IO_CTRL registers found in the
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control MMR region. These registers are required to toggle the I/O lane
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power, and control its electrical characteristics.
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ports:
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$ref: /schemas/graph.yaml#/properties/ports
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properties:
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port@0:
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$ref: /schemas/graph.yaml#/properties/port
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description: Parallel RGB input port
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port@1:
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$ref: /schemas/graph.yaml#/properties/port
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description: LVDS output port
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required:
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- port@0
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- port@1
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required:
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- reg
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- clocks
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- clock-names
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- ti,oldi-io-ctrl
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- ports
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additionalProperties: false
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...
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