Re: [PATCH v2 2/2] hwmon: add Axiado AX3000 and AX3005 PWM fan controller driver

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The interrupt handler incorrectly returns IRQ_HANDLED for unhandled device interrupts, potentially causing an IRQ storm.
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commit ac0edffb2c72d464c05c340c5df147fdcf10b0f4
Author: Petar Stepanovic <pstepanovic@axiado.com>

hwmon: add Axiado AX3000 and AX3005 PWM fan controller driver

This commit adds support for the PWM fan controller found on the Axiado AX3000
and AX3005 SoCs. It measures fan speed via a hardware tachometer interrupt and
controls the fan via an external PWM signal.

> diff --git a/drivers/hwmon/axiado-pwm-fan.c b/drivers/hwmon/axiado-pwm-fan.c
> new file mode 100644
> index 0000000000000..ac153afded47a
> --- /dev/null
> +++ b/drivers/hwmon/axiado-pwm-fan.c
[ ... ]
> +static irqreturn_t axiado_tach_irq_handler(int irq, void *dev)
> +{
> +	struct axiado_pwm_fan_ctx *ctx = dev;
> +	u32 status;
> +
> +	status = ioread32(ctx->tach_base + AX_TACH_INT_STATUS_REG);
> +
> +	if (!status)
> +		return IRQ_NONE;

[Severity: High]
Will this handler cause an IRQ storm if the hardware asserts an interrupt 
where the status is non-zero but AX_TACH_INT_PENDING is not set?

Since the condition only checks if status is zero, an unexpected bit could 
bypass the IRQ_NONE return path. The handler would then proceed to clear only 
the AX_TACH_INT_PENDING bit and return IRQ_HANDLED, leaving the actual 
hardware interrupt active and bypassing the kernel's spurious IRQ protection.

Should this explicitly check if the AX_TACH_INT_PENDING bit is set before 
processing the interrupt?

> +
> +	scoped_guard(spinlock_irqsave, &ctx->tach_lock) {
> +		ctx->tach.count = ioread32(ctx->tach_base + AX_TACH_COUNT_REG);
> +	}
> +
> +	iowrite32(AX_TACH_INT_PENDING, ctx->tach_base + AX_TACH_INT_STATUS_REG);
> +
> +	return IRQ_HANDLED;
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260903-axiado-ax3000-pwm-fan-v2-0-ef43df46163e@axiado.com?part=2