[PATCH v6 0/2] drm: bridge: Add TI tmds181 and sn65dp159 driver

[PATCH v6 0/2] drm: bridge: Add TI tmds181 and sn65dp159 driver

[Mike Looijmans]

In the past I've seen (and contributed to) hacks that model the chips as
phy or even (really!) clock drivers. Since the chip usually sits between
a signal that is (almost) HDMI and a HDMI connector, I decided to stop
lying and write it as a DRM bridge driver.

Our experience with these chips is that they work best under manual control
enabling them only once the signal is active. At low resolutions (under 4k),
the optimal setting is usually to only use redriver mode. Setting the
termination to 150-300 Ohms improves EMC performance at lower resolutions,
hence the driver enables 75-150 Ohms for HDMI2 modes and defaults to
150-300 Ohm termination for other modes.


Changes in v6:
Rename ti,mode to ti,retimer-mode
Add DRM_DISPLAY_HDMI_HELPER to Kconfig
Change "ti,mode" to "ti,retimer-mode"

Changes in v5:
ti,equalizer and ti,mode changed to enum
Rename ti,slew-rate to slew-rate
Make properties conditional for DP159/TMDS181
Remove ti,dvi-mode (always set to avoid conflict)
Really added vcc/vdd regulator support
"oe" gpio is now "reset" (reversed logic)
devicetree enums ti,equalizer and ti,mode
Always disable HDMI_SEL (formerly "dvi-mode")

Changes in v4:
Use fallback compatible
dev_err_probe, this_module, of_match_ptr
Use fallback compatible
Add vcc-supply and vdd-supply

Changes in v3:
Fix duplicate links
Add vcc-supply and vdd-supply
Fix missing type for ti,slew-rate
Lower-case hex values and use defines for EYESCAN registers
Remove equalizer code (unlikely to be used)
Remove attributes (no longer useful, undocumented)
Fix build for 6.17 kernel
Use devm_drm_bridge_alloc
Sort includes and add linux/bitfield.h
Check chip type and complain on mismatch

Changes in v2:
Document driver specific bindings like slew-rate and threshold
Use atomic_enable/disable
Use #defines for bit fields in registers
Allow HDMI 2 compliance
Filter modes on clock range
Use cross-over pixel frequency instead of manual overides
Devicetree bindings according to standards

Mike Looijmans (2):
  dt-bindings: drm/bridge: ti-tmds181: Add TI TMDS181 and SN65DP159
    bindings
  drm: bridge: Add TI tmds181 and sn65dp159 driver

 .../bindings/display/bridge/ti,tmds181.yaml   | 170 +++++++
 drivers/gpu/drm/bridge/Kconfig                |  12 +
 drivers/gpu/drm/bridge/Makefile               |   1 +
 drivers/gpu/drm/bridge/ti-tmds181.c           | 427 ++++++++++++++++++
 4 files changed, 610 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/bridge/ti,tmds181.yaml
 create mode 100644 drivers/gpu/drm/bridge/ti-tmds181.c

-- 
2.43.0

base-commit: 53e760d8949895390e256e723e7ee46618310361
branch: drm-ti-tmds181

Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@topic.nl
W: www.topic.nl

Please consider the environment before printing this e-mail

[PATCH v6 1/2] dt-bindings: drm/bridge: ti-tmds181: Add TI TMDS181 and SN65DP159 bindings

[Mike Looijmans]

Add DT binding document for TI TMDS181 and SN65DP159 HDMI retimers.

The two chips have similar register maps, but different applications
(source vs. sink).

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>

---

Changes in v6:
Rename ti,mode to ti,retimer-mode

Changes in v5:
ti,equalizer and ti,mode changed to enum
Rename ti,slew-rate to slew-rate
Make properties conditional for DP159/TMDS181
Remove ti,dvi-mode (always set to avoid conflict)

Changes in v4:
Use fallback compatible

Changes in v3:
Fix duplicate links
Add vcc-supply and vdd-supply
Fix missing type for ti,slew-rate

Changes in v2:
Document driver specific bindings like slew-rate and threshold

 .../bindings/display/bridge/ti,tmds181.yaml   | 170 ++++++++++++++++++
 1 file changed, 170 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/bridge/ti,tmds181.yaml

diff --git a/Documentation/devicetree/bindings/display/bridge/ti,tmds181.yaml b/Documentation/devicetree/bindings/display/bridge/ti,tmds181.yaml
new file mode 100644
index 000000000000..9b23221634bb
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/bridge/ti,tmds181.yaml
@@ -0,0 +1,170 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/bridge/ti,tmds181.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TMDS181 and SN65DP159 HDMI retimer/redriver chips
+
+maintainers:
+  - Mike Looijmans <mike.looijmans@topic.nl>
+
+description: |
+  Texas Instruments TMDS181 and SN65DP159 retimer and redriver chips.
+  https://www.ti.com/product/TMDS181
+  https://www.ti.com/product/SN65DP159
+  When I2C control is enabled, various pin strapping options like equalizer and
+  slew-rate are unavailable. These can be configured through I2C using the
+  properties defined here.
+  A common application for these chips is to convert AC coupled serdes outputs
+  from an FPGA or SoC into HDMI compliant signals.
+
+properties:
+  compatible:
+    oneOf:
+      - const: ti,tmds181
+      - items:
+          - const: ti,sn65dp159
+          - const: ti,tmds181
+
+  reg:
+    enum:
+      - 0x5b
+      - 0x5c
+      - 0x5d
+      - 0x5e
+
+  reset-gpios:
+    maxItems: 1
+    description: GPIO specifier for OE pin which acts as active low reset.
+
+  vdd-supply:
+    description: Core power supply, 1.1V
+
+  vcc-supply:
+    description: IO power supply, 3.3V
+
+  ports:
+    $ref: /schemas/graph.yaml#/properties/ports
+
+    properties:
+      port@0:
+        $ref: /schemas/graph.yaml#/$defs/port-base
+        unevaluatedProperties: false
+        description: Video port for HDMI (ish) input
+
+        properties:
+          endpoint:
+            $ref: /schemas/media/video-interfaces.yaml#
+            unevaluatedProperties: false
+
+      port@1:
+        $ref: /schemas/graph.yaml#/$defs/port-base
+        unevaluatedProperties: false
+        description: Video port for HDMI output (panel or bridge)
+
+        properties:
+          endpoint:
+            $ref: /schemas/media/video-interfaces.yaml#
+            unevaluatedProperties: false
+
+    required:
+      - port@0
+      - port@1
+
+  ti,retimer-mode:
+    enum:
+      - source
+      - sink
+    description:
+      Force chip to operate in "source" or "sink" mode.
+
+  ti,retimer-threshold-hz:
+    minimum: 25000000
+    maximum: 600000000
+    default: 200000000
+    description:
+      Cross-over point. Up until this pixel clock frequency the chip remains in
+      the low-power redriver mode. Above the threshold the chip should operate
+      in retimer mode.
+
+  slew-rate:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 3
+    default: 3
+    description: Set slew rate, 0 is slowest, 3 is fastest.
+
+  ti,equalizer:
+    enum:
+      - adaptive
+      - disabled
+      - fixed
+    default: adaptive
+    description: Configure the equalizer
+
+if:
+  properties:
+    compatible:
+      contains:
+        const: ti,sn65dp159
+
+then:
+  properties:
+    ti,retimer-mode:
+      default: source
+
+else:
+  properties:
+    ti,retimer-mode:
+      default: sink
+    slew-rate: false
+
+required:
+  - compatible
+  - reg
+  - ports
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        bridge@5b {
+            compatible = "ti,sn65dp159", "ti,tmds181";
+            reg = <0x5b>;
+            vdd-supply = <&vcc_1v1_reg>;
+            vcc-supply = <&vcc_3v3_reg>;
+            reset-gpios = <&gpio2 1 GPIO_ACTIVE_LOW>;
+            slew-rate = <2>;
+            ti,retimer-threshold-hz = <350000000>;
+            ti,retimer-mode = "source";
+            ti,equalizer = "disabled";
+
+            ports {
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                port@0 {
+                    reg = <0>;
+
+                    endpoint {
+                        remote-endpoint = <&encoder_out>;
+                    };
+                };
+
+                port@1 {
+                    reg = <1>;
+
+                    endpoint {
+                        remote-endpoint = <&hdmi_connector_in>;
+                    };
+                };
+            };
+        };
+    };
-- 
2.43.0


Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@topic.nl
W: www.topic.nl

Please consider the environment before printing this e-mail

Re: [PATCH v6 1/2] dt-bindings: drm/bridge: ti-tmds181: Add TI TMDS181 and SN65DP159 bindings

[Rob Herring (Arm)]

On Mon, 22 Sep 2025 14:18:44 +0200, Mike Looijmans wrote:
> Add DT binding document for TI TMDS181 and SN65DP159 HDMI retimers.
> 
> The two chips have similar register maps, but different applications
> (source vs. sink).
> 
> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
> 
> ---
> 
> Changes in v6:
> Rename ti,mode to ti,retimer-mode
> 
> Changes in v5:
> ti,equalizer and ti,mode changed to enum
> Rename ti,slew-rate to slew-rate
> Make properties conditional for DP159/TMDS181
> Remove ti,dvi-mode (always set to avoid conflict)
> 
> Changes in v4:
> Use fallback compatible
> 
> Changes in v3:
> Fix duplicate links
> Add vcc-supply and vdd-supply
> Fix missing type for ti,slew-rate
> 
> Changes in v2:
> Document driver specific bindings like slew-rate and threshold
> 
>  .../bindings/display/bridge/ti,tmds181.yaml   | 170 ++++++++++++++++++
>  1 file changed, 170 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/bridge/ti,tmds181.yaml
> 

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>