Re: [PATCH 1/3] dt-bindings: clock: qcom: add mmcc-msm8660 clock IDs

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Silent failure to unhalt MMSS fabric if qcom_rpm is not bound yet.
--

commit 7a52c01ee4faffcac27f221b8547899fcd741b7b
Author: Herman van Hazendonk <github.com@herrie.org>

clk: qcom: add MSM8x60 MMCC driver

Add a clock driver for the Multimedia Clock Controller (MMCC) on the
MSM8x60 family (MSM8260/MSM8660/APQ8060) - the Scorpion-class
generation that preceded MSM8960's Krait CPUs.

> diff --git a/drivers/clk/qcom/mmcc-msm8660.c b/drivers/clk/qcom/mmcc-msm8660.c
> new file mode 100644
> index 0000000000000..50781a63e65fe
> --- /dev/null
> +++ b/drivers/clk/qcom/mmcc-msm8660.c
[ ... ]
> +static void mmcc_msm8660_unhalt_fabric_ports(struct device *dev)
> +{
> +	struct device_node *rpm_node;
> +	struct platform_device *rpm_pdev;
> +	struct device_link *link;
> +	struct qcom_rpm *rpm;
> +	/* halt_data[0]=0 = CLK_UNHALT for all bits; halt_data[1] = port mask */
> +	u32 mmss_halt[2] = {0, GENMASK(13, 0)};
> +	int rc;
[ ... ]
> +	rpm = dev_get_drvdata(&rpm_pdev->dev);
> +	if (!rpm) {
> +		/*
> +		 * Supplier exists but has not bound yet -- skip the
> +		 * unhalt rather than blocking mmcc probe; downstream
> +		 * MMSS clients will be enabled on demand.
> +		 */
> +		put_device(&rpm_pdev->dev);
> +		return;
> +	}

[Severity: High]
Does this code silently fail to unhalt the MMSS fabric if the qcom_rpm driver
has not yet probed?

If dev_get_drvdata() returns NULL because the RPM driver hasn't bound yet,
this function returns without an error. Since mmcc_msm8660_probe() calls this
and ignores any failure, it will complete probe successfully but leave the
MMSS fabric permanently halted.

The comment here states "downstream MMSS clients will be enabled on demand",
but this contradicts the block comment above indicating that mainline GDSC
does not implement on-demand unhalting. When multimedia hardware later powers
on and attempts DMA, the hardware queues will freeze and stall the system.

Should mmcc_msm8660_unhalt_fabric_ports() return an int so we can pass
-EPROBE_DEFER back to the probe function to wait for the RPM driver?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260602043623.285901-1-github.com@herrie.org?part=1