Re: [PATCH v2] ARM: dts: imx7d-pico-pi: add OV5645 camera support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Critical] The OV5645 digital core voltage (`vddd-supply`) is mapped to a 1.8V regulator, violating the sensor's maximum voltage rating.
- [High] The MIPI CSI core wrap clock is severely underclocked to 24MHz, causing performance bottlenecks and dropped frames.
--

commit dd6924fa219eeb7e7a60387b7bc6b921c2ef8a7b
Author: Lech Perczak <lech.perczak@gmail.com>

ARM: dts: imx7d-pico-pi: add OV5645 camera support

Add OV5645 camera device node and enable relevant components in the video
capture data path. It establishes an image path through MIPI-CSIS and CSI
peripherals to capture pictures at 1280x960px resolution.

Link: https://github.com/technexion-android/kernel_imx/blob/ce8fd74abf518dac0a09e8dcb37f3496f6375124/arch/arm/boot/dts/imx7d-pico.dtsi#L874 [1]

> diff --git a/arch/arm/boot/dts/nxp/imx/imx7d-pico-pi.dts b/arch/arm/boot/dts/nxp/imx/imx7d-pico-pi.dts
> index 62221131336f1..6a6c3c743b41b 100644
> --- a/arch/arm/boot/dts/nxp/imx/imx7d-pico-pi.dts
> +++ b/arch/arm/boot/dts/nxp/imx/imx7d-pico-pi.dts
> @@ -59,6 +59,33 @@ polytouch: touchscreen@38 {
>  		touchscreen-size-x = <800>;
>  		touchscreen-size-y = <480>;
>  	};
> +
> +	camera@3c {
> +		compatible = "ovti,ov5645";
> +		reg = <0x3c>;
> +
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&pinctrl_camera>;
> +
> +		clocks = <&clks IMX7D_CLKO1_ROOT_DIV>;
> +		assigned-clocks = <&clks IMX7D_CLKO1_ROOT_DIV>;
> +		assigned-clock-rates = <24000000>;
> +
> +		enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
> +		reset-gpios = <&gpio1 5 GPIO_ACTIVE_LOW>;
> +
> +		vdda-supply = <&reg_2p5v>;
> +		vdddo-supply = <&reg_vref_1v8>;
> +		vddd-supply = <&reg_vref_1v8>;

[Severity: Critical]
Is the vddd-supply voltage correct here?

According to the ovti,ov5645.yaml bindings and hardware specifications, the
digital core voltage (vddd-supply) should strictly be 1.5V.

Connecting this to a 1.8V regulator appears to subject the sensor to an
overvoltage condition that exceeds its maximum ratings, which might lead to
overheating or hardware damage.

> +
> +		port {
> +			ov5645_to_mipi_csi2: endpoint {
> +				remote-endpoint = <&mipi_csi2_in>;
> +				clock-lanes = <0>;
> +				data-lanes = <1 2>;
> +			};
> +		};
> +	};
>  };
>  
[ ... ]
> +&mipi_csi {
> +	status = "okay";
> +	assigned-clocks = <&clks IMX7D_MIPI_CSI_ROOT_CLK>;
> +	assigned-clock-rates = <24000000>;

[Severity: High]
Could this be the cause of the performance bottleneck mentioned in the
commit message?

The nxp,imx-mipi-csi2.yaml bindings indicate that the CSI core wrap clock
should be configured to 166MHz (<166000000>).

Setting it to 24MHz limits the processing bandwidth to ~24 Mpixels/sec,
which seems insufficient for streaming uncompressed 1280x960 video. Setting
the clock to 166MHz might resolve the underpowered streaming performance.

> +
> +	ports {
> +		port@0 {
> +			reg = <0>;
> +
> +			mipi_csi2_in: endpoint {
> +				remote-endpoint = <&ov5645_to_mipi_csi2>;
> +				data-lanes = <1 2>;
> +			};
> +		};
> +	};
> +};

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260527005213.6019-1-lech.perczak@gmail.com?part=1