Re: [PATCH v2 1/3] spi: nxp-fspi: use devm runtime PM enablement

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Removing pm_runtime_disable() from nxp_fspi_cleanup() while keeping manual clock disablement causes a deterministic double clock disable (reference count underflow) on driver unbind and probe error paths.
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--- Patch [1]: [PATCH v2 1/3] spi: nxp-fspi: use devm runtime PM enablement ---
commit 274e174a430a74bbdd5c40d6aaca37aea56ac764
Author: Jiawen Liu <[email protected]>

spi: nxp-fspi: use devm runtime PM enablement

This commit replaces open-coded runtime PM enablement with
devm_pm_runtime_enable() and uses PM_RUNTIME_ACQUIRE_AUTOSUSPEND() to
simplify the error path and avoid leaving runtime PM state behind on
failure.

> diff --git a/drivers/spi/spi-nxp-fspi.c b/drivers/spi/spi-nxp-fspi.c
> index 1e36ae084dd86..6be78712b5343 100644
> --- a/drivers/spi/spi-nxp-fspi.c
> +++ b/drivers/spi/spi-nxp-fspi.c
> @@ -1275,7 +1275,6 @@ static void nxp_fspi_cleanup(void *data)
>  	/* disable the hardware */
>  	fspi_writel(f, FSPI_MCR0_MDIS, f->iobase + FSPI_MCR0);
>  
> -	pm_runtime_disable(f->dev);
>  	pm_runtime_put_noidle(f->dev);
>  	nxp_fspi_clk_disable_unprep(f);

[Severity: High]
Does removing pm_runtime_disable() here cause a double clock disable
during driver unbind or late probe failure?

When devres executes nxp_fspi_cleanup(), it drops the usage count via
pm_runtime_put_noidle() and manually disables the clocks with
nxp_fspi_clk_disable_unprep(). However, the device remains in the
RPM_ACTIVE state.

Later in the devres cleanup phase, the action registered by
devm_pm_runtime_enable() executes and clears autosuspend. Because the PM
usage count is 0 and autosuspend is now disabled, the PM core
synchronously transitions the device to RPM_SUSPENDED by executing the
driver's runtime suspend callback.

Will the runtime suspend callback then blindly invoke
nxp_fspi_clk_disable_unprep() a second time, triggering a clock reference
count underflow?

[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1