Re: [PATCH v2 12/24] arm64: dts: qcom: sm8550: 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 OS PDC DRV register window to 0x10000 in the DT without updating the qcom-pdc driver triggers a spurious boot warning and nullifies the size reduction.
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commit af73b863314fd2efa87dbeb8a5636a342659cea6
Author: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>

arm64: dts: qcom: sm8550: Reduce OS PDC DRV span to 0x10000

This commit reduces the OS PDC DRV register window size from 0x30000 to
0x10000 in the sm8550 device tree.

> diff --git a/arch/arm64/boot/dts/qcom/sm8550.dtsi b/arch/arm64/boot/dts/qcom/sm8550.dtsi
> index 912525e9bca6f..de04610ef47e8 100644
> --- a/arch/arm64/boot/dts/qcom/sm8550.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sm8550.dtsi
> @@ -4245,7 +4245,7 @@ usb_1_dwc3_ss: endpoint {
>  
>  		pdc: interrupt-controller@b220000 {
>  			compatible = "qcom,sm8550-pdc", "qcom,pdc";
> -			reg = <0 0x0b220000 0 0x30000>, <0 0x174000f0 0 0x64>;
> +			reg = <0 0x0b220000 0 0x10000>, <0 0x174000f0 0 0x64>;

[Severity: Medium]
Does this reduction trigger a boot warning and map 0x30000 bytes anyway?

Looking at drivers/irqchip/qcom-pdc.c, QCOM_PDC_SIZE is hardcoded to
0x30000.

The driver calculates the actual mapping size using:
res_size = max_t(resource_size_t, resource_size(&res), QCOM_PDC_SIZE);

With the DT size reduced to 0x10000, res_size still evaluates to 0x30000.
The driver then checks if (res_size > resource_size(&res)), which becomes
true, and unconditionally emits pr_warn("%pOF: invalid reg size, please fix
DT\n", node) on boot.

Furthermore, it proceeds to call ioremap(res.start, res_size), mapping
0x30000 bytes instead of the intended 0x10000. This seems to nullify the
size reduction introduced by this patch.

>  			qcom,pdc-ranges = <0 480 94>, <94 609 31>,
>  					  <125 63 1>, <126 716 12>,
>  					  <138 251 5>;

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Sashiko AI review · https://sashiko.dev/#/patchset/20260527094333.2311731-1-mukesh.ojha@oss.qualcomm.com?part=12