Re: [PATCH v5 06/23] dmaengine: ste_dma40: Check runtime PM in IRQ

[Frank Li <Frank.li@oss.nxp.com>]

On Sun, Sep 20, 2026 at 08:59:41PM +0200, Linus Walleij wrote:
> d40_handle_interrupt() reads DMA40 interrupt registers unconditionally. A
> spurious interrupt can arrive while the device is runtime suspended, after
> dma40_runtime_suspend() has disabled the GCC clock.
>
> Avoid touching the registers unless the device is runtime active by taking
> a conditional runtime PM reference. Return IRQ_NONE when the device is
> suspended, and drop the reference after handling an active interrupt.
>
> When CONFIG_PM is disabled, pm_runtime_get_if_active() returns -EINVAL even
> though the registers remain accessible. Keep handling interrupts in that
> configuration and only drop the runtime PM reference when one was acquired.
>
> Fixes: 7fb3e75e1833 ("dmaengine/ste_dma40: support pm in dma40")
> Reported-by: sashiko-bot@kernel.org
> Closes: https://lore.kernel.org/dmaengine/20260819225114.AE1511F000E9@smtp.kernel.org/
> Assisted-by: LLM
> Signed-off-by: Linus Walleij <linusw@kernel.org>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

>  drivers/dma/ste_dma40.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
> index 1d02226ab5ff..58128a980847 100644
> --- a/drivers/dma/ste_dma40.c
> +++ b/drivers/dma/ste_dma40.c
> @@ -1798,6 +1798,11 @@ static irqreturn_t d40_handle_interrupt(int irq, void *data)
>  	u32 *regs = base->regs_interrupt;
>  	struct d40_interrupt_lookup *il = base->gen_dmac.il;
>  	u32 il_size = base->gen_dmac.il_size;
> +	int ret;
> +
> +	ret = pm_runtime_get_if_active(base->dev);
> +	if (IS_ENABLED(CONFIG_PM) && ret <= 0)
> +		return IRQ_NONE;
>
>  	spin_lock(&base->interrupt_lock);
>
> @@ -1846,6 +1851,9 @@ static irqreturn_t d40_handle_interrupt(int irq, void *data)
>
>  	spin_unlock(&base->interrupt_lock);
>
> +	if (ret > 0)
> +		pm_runtime_put_autosuspend(base->dev);
> +
>  	return IRQ_HANDLED;
>  }
>
>
> --
> 2.55.0
>