On Fri, Mar 06, 2026 at 03:52:41PM +0800, Yu-Chun Lin wrote:

quoted

+      input-voltage-microvolt:
+        description: |
+          Select the input receiver voltage domain for the pin.
+          Valid arguments are:
+          - 1800000: 1.8V input logic level
+          - 3300000: 3.3V input logic level
+        enum: [1800000, 3300000]
+
+      drive-push-pull: true
+
+      power-source:
+        description: |
+          Valid arguments are described as below:
+          0: power supply of 1.8V
+          1: power supply of 3.3V
+        enum: [0, 1]

Isn't this duplicating input-voltage-microvolt? Where do you use it in the
driver?

No, this is not a duplication. power-source is used to configure the output voltage,
whereas input-voltage-microvolt controls the input logic thresholds.

Both are handled in rtd_pconf_parse_conf(), which is called by rtd_pin_config_set().

quoted

+
+      slew-rate:
+        description: |
+          Valid arguments are described as below:
+            0: ~1ns falling time
+            1: ~10ns falling time
+            2: ~20ns falling time
+            3: ~30ns falling time
+        enum: [0, 1, 2, 3]

If you have specific values, why not using 1/10/20/30?

I will use specific values in v3.

quoted

+
+      realtek,drive-strength-p:
+        description: |
+          Some of pins can be driven using the P-MOS and N-MOS

transistor to

quoted

+          achieve finer adjustments. The block-diagram representation is

as

quoted

+          follows:
+                         VDD
+                          |
+                      ||--+
+               +-----o||     P-MOS-FET
+               |      ||--+
+          IN --+          +----- out
+               |      ||--+
+               +------||     N-MOS-FET
+                      ||--+
+                          |
+                         GND
+          The driving strength of the P-MOS/N-MOS transistors impacts

the

quoted

+          waveform's rise/fall times. Greater driving strength results in
+          shorter rise/fall times. Each P-MOS and N-MOS transistor

offers

quoted

+          8 configurable levels (0 to 7), with higher values indicating
+          greater driving strength, contributing to achieving the desired
+          speed.
+
+          The realtek,drive-strength-p is used to control the driving

strength

quoted

+          of the P-MOS output.
+
+          This value is not a simple count of transistors. Instead, it
+          represents a weighted configuration. There is a base driving
+          capability (even at value 0), and each bit adds a different

weight to

quoted

+          the total strength. The resulting current is non-linear and varies
+          significantly based on the IO voltage (1.8V vs 3.3V) and the

specific

quoted

+          pad group.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        minimum: 0
+        maximum: 7
+
+      realtek,drive-strength-n:
+        description: |
+          Similar to the realtek,drive-strength-p, the

realtek,drive-strength-n

quoted

+          is used to control the driving strength of the N-MOS output.
+
+          This property uses the same weighted configuration logic

where values

quoted

+          0-7 represent non-linear strength adjustments rather than a

transistor

quoted

+          count.
+
+          Higher values indicate greater driving strength, resulting in

shorter

quoted

+          fall times.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        minimum: 0
+        maximum: 7
+
+      realtek,pulse-width-adjust:
+        description: |
+          An integer describing the level to adjust the output pulse width,

it

quoted

+          provides a fixed nanosecond-level adjustment to the

rising/falling

quoted

+          edges of an existing signal. It is used for Signal Integrity tuning
+          (adding/subtracting delay to fine-tune the high/low duration),

rather

quoted

+          than generating a specific PWM frequency.
+
+          Valid arguments are described as below:
+          0: 0ns
+          2: + 0.25ns
+          3: + 0.5ns
+          4: -0.25ns
+          5: -0.5ns
+        $ref: /schemas/types.yaml#/definitions/uint32
+        enum: [0, 2, 3, 4, 5]
+
+      realtek,high-vil-microvolt:
+        description: |
+          The threshold value for the input receiver's LOW recognition

(VIL).

quoted

+
+          This property is used to address specific HDMI I2C compatibility
+          issues where some sinks (TVs) have weak pull-down capabilities

and

quoted

+          fail to pull the bus voltage below the standard VIL threshold
+          (~0.7V).
+
+          Setting this property to 1100000 (1.1V) enables a specialized

input

quoted

+          receiver mode that raises the effective VIL threshold to improve
+          detection.
+        enum: [1100000]
+
+    required:
+      - pins
+
+    additionalProperties: false
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    pinctrl@4e000 {
+        compatible = "realtek,rtd1625-iso-pinctrl";
+        reg = <0x4e000 0x130>;
+
+        emmc-hs200-pins {
+            pins = "emmc_clk",
+                   "emmc_cmd",
+                   "emmc_data_0",
+                   "emmc_data_1",
+                   "emmc_data_2",
+                   "emmc_data_3",
+                   "emmc_data_4",
+                   "emmc_data_5",
+                   "emmc_data_6",
+                   "emmc_data_7";
+            function = "emmc";
+            realtek,drive-strength-p = <0x2>;
+            realtek,drive-strength-n = <0x2>;

These are not hex, but simple decimals

I will change them to <2>.

Best Regards,
Yu-Chun

quoted

+        };
+
+        i2c-0-pins {
+            pins = "gpio_12",
+                   "gpio_13";
+            function = "i2c0";
+            drive-strength = <4>;
+        };
+    };
--
2.34.1