Re: [PATCH v5] i2c: imx: mark I2C adapter when hardware is powered down

[Andi Shyti <andi.shyti@kernel.org>]

Hi Oleksij,

Any chance you can give this a review?

Thanks,
Andi

On Mon, May 25, 2026 at 11:04:00AM +0800, Carlos Song (OSS) wrote:
> From: Carlos Song <carlos.song@nxp.com>
> 
> On some i.MX platforms, certain I2C client drivers keep a periodic
> workqueue which continues to trigger I2C transfers.
> 
> During system suspend/resume, there exists a time window between:
>   - suspend_noirq and the system entering suspend
>   - the system starting to resume and resume_noirq
> 
> In this window, the I2C controller resources such as clock and pinctrl
> may already be disabled or not yet restored.
> 
> If a workqueue triggers an I2C transfer in this period, the driver
> attempts to access I2C registers while the hardware resources are
> unavailable, which may lead to system hang.
> 
> Mark the I2C adapter as suspended during noirq suspend and block new
> transfers until resume, ensuring that I2C transfers are only issued
> when hardware resources are available.
> 
> Fixes: 358025ac091e ("i2c: imx: make controller available until system suspend_noirq() and from resume_noirq()")
> Cc: stable@vger.kernel.org
> Signed-off-by: Carlos Song <carlos.song@nxp.com>
> ---
> Change for v5:
>   - Remake commit log including the issue detail from Mukesh's
>     suggestion.
> Change for v4:
>   - Restore hrtimer when pm_runtime_force_suspend failed when slave mode
>     enabled.
> Change for v3:
>   - Add hrtimer_cancel in i2c_imx_suspend_noirq to cancel slave_timer for
>     safe suspend in i2c slave mode.
> Change for v2:
>   - Call i2c_mark_adapter_suspended() before pm_runtime_force_suspend()
>     to prevent potential deadlock if a transfer is active during suspend.
>   - Roll back with i2c_mark_adapter_resumed() if pm_runtime_force_suspend()
>     fails.
> ---
>  drivers/i2c/busses/i2c-imx.c | 45 ++++++++++++++++++++++++++++++++++--
>  1 file changed, 43 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 28313d0fad37..73317ddd5f02 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -1922,6 +1922,47 @@ static int i2c_imx_runtime_resume(struct device *dev)
>  	return 0;
>  }
>  
> +static int __maybe_unused i2c_imx_suspend_noirq(struct device *dev)
> +{
> +	struct imx_i2c_struct *i2c_imx = dev_get_drvdata(dev);
> +	int ret;
> +
> +	i2c_mark_adapter_suspended(&i2c_imx->adapter);
> +
> +	/*
> +	 * Cancel the slave timer before powering down to prevent
> +	 * i2c_imx_slave_timeout() from accessing hardware registers
> +	 * while the clock is disabled.
> +	 */
> +	hrtimer_cancel(&i2c_imx->slave_timer);
> +
> +	ret = pm_runtime_force_suspend(dev);
> +	if (ret) {
> +		i2c_mark_adapter_resumed(&i2c_imx->adapter);
> +		if (i2c_imx->slave) {
> +			hrtimer_forward_now(&i2c_imx->slave_timer, I2C_IMX_CHECK_DELAY);
> +			hrtimer_restart(&i2c_imx->slave_timer);
> +		}
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused i2c_imx_resume_noirq(struct device *dev)
> +{
> +	struct imx_i2c_struct *i2c_imx = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = pm_runtime_force_resume(dev);
> +	if (ret)
> +		return ret;
> +
> +	i2c_mark_adapter_resumed(&i2c_imx->adapter);
> +
> +	return 0;
> +}
> +
>  static int i2c_imx_suspend(struct device *dev)
>  {
>  	/*
> @@ -1955,8 +1996,8 @@ static int i2c_imx_resume(struct device *dev)
>  }
>  
>  static const struct dev_pm_ops i2c_imx_pm_ops = {
> -	NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> -				  pm_runtime_force_resume)
> +	NOIRQ_SYSTEM_SLEEP_PM_OPS(i2c_imx_suspend_noirq,
> +				  i2c_imx_resume_noirq)
>  	SYSTEM_SLEEP_PM_OPS(i2c_imx_suspend, i2c_imx_resume)
>  	RUNTIME_PM_OPS(i2c_imx_runtime_suspend, i2c_imx_runtime_resume, NULL)
>  };
> -- 
> 2.43.0
>