Re: [PATCH v2 14/24] arm64: dts: qcom: sm4450: Reduce OS PDC DRV span to 0x10000

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Reducing the `reg` span to 0x10000 in the device tree is futile without an accompanying driver change and will intentionally trigger a boot warning.
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commit befb5e3c3aa5e0f54a7fff3d0f4a5e96013f4a7e
Author: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>

arm64: dts: qcom: sm4450: Reduce OS PDC DRV span to 0x10000

The OS PDC DRV register window on sm4450 spans 0x10000 bytes, so this
commit reduces the size of the first reg entry from 0x30000 to 0x10000.

> diff --git a/arch/arm64/boot/dts/qcom/sm4450.dtsi b/arch/arm64/boot/dts/qcom/sm4450.dtsi
> --- a/arch/arm64/boot/dts/qcom/sm4450.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sm4450.dtsi
> @@ -464,7 +464,7 @@ dispcc: clock-controller@af00000 {
>  
>  		pdc: interrupt-controller@b220000 {
>  			compatible = "qcom,sm4450-pdc", "qcom,pdc";
> -			reg = <0 0x0b220000 0 0x30000>, <0 0x174000f0 0 0x64>;
> +			reg = <0 0x0b220000 0 0x10000>, <0 0x174000f0 0 0x64>;

[Severity: Medium]
Will this change cause a boot warning and fail to actually reduce the mapping
size?

Looking at the qcom-pdc driver in drivers/irqchip/qcom-pdc.c, it enforces a
minimum mapping size of QCOM_PDC_SIZE (0x30000) for all devices to maintain
backward compatibility. In qcom_pdc_probe(), it calculates the size as:

	res_size = max_t(resource_size_t, resource_size(&res), QCOM_PDC_SIZE);

If the device tree provides a size smaller than 0x30000 (like 0x10000), the
driver automatically expands the mapping back to 0x30000 and logs a warning:
"%pOF: invalid reg size, please fix DT".

Since there are no accompanying driver changes to gracefully accept the smaller
size for newer compatibles like "qcom,sm4450-pdc", does this patch introduce a
spurious warning on every boot without achieving the intended mapping
reduction?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260527094333.2311731-1-mukesh.ojha@oss.qualcomm.com?part=14