Re: [PATCH 5/7] can: m_can: fix CAN state in system PM

["Markus Schneider-Pargmann" <msp@baylibre.com>]

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On Tue Aug 12, 2025 at 7:36 PM CEST, Marc Kleine-Budde wrote:
> A suspend/resume cycle on a down interface results in the interface
> coming up in Error Active state. A suspend/resume cycle on an Up
> interface will always result in Error Active state, regardless of the
> actual CAN state.
>
> During suspend, only set running interfaces to CAN_STATE_SLEEPING.
> During resume only touch the CAN state of running interfaces. For
> wakeup sources, set the CAN state depending on the Protocol Status
> Regitser (PSR), for non wakeup source interfaces m_can_start() will do
> the same.
>
> Fixes: e0d1f4816f2a ("can: m_can: add Bosch M_CAN controller support")
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Reviewed-by: Markus Schneider-Pargmann <msp@baylibre.com>

> ---
>  drivers/net/can/m_can/m_can.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 310a907cbb7e..149f3a8b5f7e 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -2507,12 +2507,11 @@ int m_can_class_suspend(struct device *dev)
>  		}
>  
>  		m_can_clk_stop(cdev);
> +		cdev->can.state = CAN_STATE_SLEEPING;
>  	}
>  
>  	pinctrl_pm_select_sleep_state(dev);
>  
> -	cdev->can.state = CAN_STATE_SLEEPING;
> -
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(m_can_class_suspend);
> @@ -2525,14 +2524,14 @@ int m_can_class_resume(struct device *dev)
>  
>  	pinctrl_pm_select_default_state(dev);
>  
> -	cdev->can.state = CAN_STATE_ERROR_ACTIVE;
> -
>  	if (netif_running(ndev)) {
>  		ret = m_can_clk_start(cdev);
>  		if (ret)
>  			return ret;
>  
>  		if (cdev->pm_wake_source) {
> +			u32 reg_psr;
> +
>  			/* Restore active interrupts but disable coalescing as
>  			 * we may have missed important waterlevel interrupts
>  			 * between suspend and resume. Timers are already
> @@ -2544,6 +2543,9 @@ int m_can_class_resume(struct device *dev)
>  			if (cdev->ops->init)
>  				ret = cdev->ops->init(cdev);
>  
> +			reg_psr = m_can_read(cdev, M_CAN_PSR);
> +			cdev->can.state = m_can_can_state_get_by_psr(reg_psr);
> +
>  			m_can_write(cdev, M_CAN_IE, cdev->active_interrupts);
>  		} else {
>  			ret  = m_can_start(ndev);


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