Enable the "i2c2" bus on header pins 3 (I2C_SDA_M1)
and 5 (I2C2_SCL_M1) of the Orange Pi 3B board.

As documented on http://www.orangepi.org/img/pi3b/0719-pi3b-19.png,
such pins are the only ones offering I2C functionality
without conflicting with other SoC blocks.

Signed-off-by: Michael Opdenacker <michael.opdenacker@rootcommit.com>
---
 arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi b/arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi
index d539570f531e..e2f0ccc6dbe7 100644
--- a/arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi
@@ -435,6 +435,11 @@ regulator-state-mem {
 	};
 };
 
+&i2c2 {
+	pinctrl-0 = <&i2c2m1_xfer>;
+	status = "okay";
+};
+
 &i2s0_8ch {
 	status = "okay";
 };

---
base-commit: 8e621c9a337555c914cf1664605edfaa6f839774
change-id: 20251120-orangepi3-enable-i2c2-fe6d25ec681a

Best regards,
-- 
Michael Opdenacker <michael.opdenacker@rootcommit.com>

Hi Michael,

On 11/20/2025 8:00 PM, Michael Opdenacker wrote:
> Enable the "i2c2" bus on header pins 3 (I2C_SDA_M1)
> and 5 (I2C2_SCL_M1) of the Orange Pi 3B board.
> 
> As documented on http://www.orangepi.org/img/pi3b/0719-pi3b-19.png
> such pins are the only ones offering I2C functionality
> without conflicting with other SoC blocks.

This is strictly not true, these pins are by default used as GPIO, this
patch change them to use the I2C2 func, something that should normally
be enabled in an overlay.

Functions for these pins:

	func 0		func 1

	GPIO4_B4_d	I2C2_SDA_M1
	GPIO4_B5_d	I2C2_SCL_M1

> 
> Signed-off-by: Michael Opdenacker <michael.opdenacker@rootcommit.com>
> ---
>  arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi b/arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi
> index d539570f531e..e2f0ccc6dbe7 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi
> @@ -435,6 +435,11 @@ regulator-state-mem {
>  	};
>  };
>  
> +&i2c2 {
> +	pinctrl-0 = <&i2c2m1_xfer>;

pinctrl-names should also be added here.

> +	status = "okay";

As mentioned above, this should be enabled in an DT overlay not in the
board DT.

Regards,
Jonas

> +};
> +
>  &i2s0_8ch {
>  	status = "okay";
>  };
> 
> ---
> base-commit: 8e621c9a337555c914cf1664605edfaa6f839774
> change-id: 20251120-orangepi3-enable-i2c2-fe6d25ec681a
> 
> Best regards,

Hi Jonas

Thanks for the review!

On 11/26/25 09:40, Jonas Karlman wrote:
> Hi Michael,
>
> On 11/20/2025 8:00 PM, Michael Opdenacker wrote:
>> Enable the "i2c2" bus on header pins 3 (I2C_SDA_M1)
>> and 5 (I2C2_SCL_M1) of the Orange Pi 3B board.
>>
>> As documented on http://www.orangepi.org/img/pi3b/0719-pi3b-19.png
>> such pins are the only ones offering I2C functionality
>> without conflicting with other SoC blocks.
> This is strictly not true, these pins are by default used as GPIO, this
> patch change them to use the I2C2 func, something that should normally
> be enabled in an overlay.
>
> Functions for these pins:
>
> 	func 0		func 1
>
> 	GPIO4_B4_d	I2C2_SDA_M1
> 	GPIO4_B5_d	I2C2_SCL_M1


Correct. My idea was that GPIOs are easy to get on other pins, and I 
found that I2C2 on such pins would be a convenient default.

>
>> Signed-off-by: Michael Opdenacker <michael.opdenacker@rootcommit.com>
>> ---
>>   arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi b/arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi
>> index d539570f531e..e2f0ccc6dbe7 100644
>> --- a/arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi
>> +++ b/arch/arm64/boot/dts/rockchip/rk3566-orangepi-3b.dtsi
>> @@ -435,6 +435,11 @@ regulator-state-mem {
>>   	};
>>   };
>>   
>> +&i2c2 {
>> +	pinctrl-0 = <&i2c2m1_xfer>;
> pinctrl-names should also be added here.


Actually, the "pinctrl-names" property is already available in the 
definition of i2c2. That's why I didn't add it again.

>
>> +	status = "okay";
> As mentioned above, this should be enabled in an DT overlay not in the
> board DT.

I don't mind if my patch is removed, no hard feelings :)

BTW, is there a convenient location for sharing overlays like these? 
Some overlays are sometimes tricky to develop, and sharing them with 
others is useful for the community.  I guess the question was asked 
before, but I don't know its answer :)

Thanks again
Cheers
Michael.

-- 
Michael Opdenacker
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