Re: [PATCH 5/8] interconnect: qcom: icc-rpm: Allow negative QoS offset

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] interconnect: qcom: icc-rpm: qos_offset left unsigned in struct qcom_icc_desc
--

commit 3e9f9997842746ad0c0d3e4f86234e2fec24e800
Author: Konrad Dybcio <konradybcio@kernel.org>

interconnect: qcom: icc-rpm: Allow negative QoS offset

This commit changes qos_offset in struct qcom_icc_provider from unsigned int
to int to support negative QoS register offsets on platforms such as MSM8998.

> diff --git a/drivers/interconnect/qcom/icc-rpm.h b/drivers/interconnect/qcom/icc-rpm.h
> index d2c5f45eeedf4..d0ffc042e926b 100644
> --- a/drivers/interconnect/qcom/icc-rpm.h
> +++ b/drivers/interconnect/qcom/icc-rpm.h
> @@ -57,7 +57,7 @@ struct qcom_icc_provider {
>  	struct icc_provider provider;
>  	enum qcom_icc_type type;
>  	struct regmap *regmap;
> -	unsigned int qos_offset;
> +	int qos_offset;
>  	u16 ab_coeff;
>  	u16 ib_coeff;
>  	u32 bus_clk_rate[QCOM_SMD_RPM_STATE_NUM];

[Severity: Low]
Should qos_offset in struct qcom_icc_desc also be changed from unsigned int
to int?

Platform interconnect drivers initialize qos_offset in struct qcom_icc_desc,
which is still declared as unsigned int in drivers/interconnect/qcom/icc-rpm.h:

struct qcom_icc_desc {
	...
	const struct regmap_config *regmap_cfg;
	unsigned int qos_offset;
	u16 ab_coeff;
	...
};

When a descriptor initializes qos_offset to a negative value (such as -0x300
on MSM8998 BIMC) and qnoc_probe() in drivers/interconnect/qcom/icc-rpm.c
copies it to the provider:

	qp->type = desc->type;
	qp->qos_offset = desc->qos_offset;

leaving desc->qos_offset unsigned causes an implicit negative-to-unsigned
conversion at initialization and an unsigned-to-signed conversion in
qnoc_probe().

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261019-msm8998-icc-v1-0-c2da3934b6c8@oss.qualcomm.com?part=5