Re: [PATCH net-next v8 2/3] ptp: Add driver for R-Car Gen4

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential
issues to consider:
- [Medium] ptp: rcar_gen4: check pm_runtime_resume_and_get() in
  ptp_rcar_gen4_probe()
- [Low] ptp: rcar_gen4: missing PTPTMDC_REG write on error in
  ptp_rcar_gen4_probe()
--

commit 0b281490f8408b05b34c2584004769891977d1ff
Author: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

ptp: Add driver for R-Car Gen4

This commit adds a PTP clock driver for the system-wide gPTP timer found
on Renesas R-Car Gen4 SoCs.

> diff --git a/drivers/ptp/ptp_rcar_gen4.c b/drivers/ptp/ptp_rcar_gen4.c
> new file mode 100644
> index 0000000000000..e82b6c5abc306
> --- /dev/null
> +++ b/drivers/ptp/ptp_rcar_gen4.c

[ ... ]

> +static int ptp_rcar_gen4_probe(struct platform_device *pdev)
> +{

[ ... ]

> +	pm_runtime_enable(dev);
> +	pm_runtime_resume_and_get(dev);

[Severity: Medium]
Should ptp_rcar_gen4_probe() check the return value of
pm_runtime_resume_and_get()?  If runtime resume fails, the device remains
suspended and its usage reference is already dropped, so the following
iowrite32() calls access unclocked registers and a later
pm_runtime_put_sync() in the error or remove path will underflow
dev->power.usage_count.

> +
> +	iowrite32(priv->default_addend, priv->base + PTPTIVC0_REG);
> +	iowrite32(1, priv->base + PTPTMEC_REG);
> +
> +	priv->clock = ptp_clock_register(&priv->info, dev);
> +	if (IS_ERR(priv->clock)) {
> +		pm_runtime_put_sync(dev);
> +		pm_runtime_disable(dev);
> +		return PTR_ERR(priv->clock);
> +	}

[Severity: Low]
Should the ptp_clock_register() error path also write 1 to PTPTMDC_REG as
ptp_rcar_gen4_remove() does?  On R-Car S4 and V4H the gPTP block shares
its module clock with the Ethernet controller, so pm_runtime_put_sync()
does not gate the clock while the Ethernet device is active, leaving the
hardware timer running after a failed probe.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261110080727.2377040-1-niklas.soderlund+renesas@ragnatech.se?part=2