Re: [PATCH v3 1/3] can: m_can: allow keeping the transceiver running in suspend

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

Hi Martin,

On Mon, Nov 13, 2023 at 02:14:50PM +0100, Martin Hundebøll wrote:
> Add a flag to the device class structure that leaves the chip in a
> running state with rx interrupt enabled, so that an m_can device driver
> can configure and use the interrupt as a wakeup source.
> 
> Signed-off-by: Martin Hundebøll <martin@geanix.com>
> ---
> 
> Change in v3:
>  * Replaced the added function parameter with a property in
>    struct m_can_classdev.
> 
> Changes in v2:
>  * Fixed comment formatting
>  * Updated m_can_class_{suspend,resume} calls in m_can_pci.c too
>  * Skipped calling m_can_start() when resuming a wake-source device
> 
>  drivers/net/can/m_can/m_can.c          | 22 +++++++++++++++++-----
>  drivers/net/can/m_can/m_can.h          |  1 +
>  drivers/net/can/m_can/m_can_pci.c      |  1 +
>  drivers/net/can/m_can/m_can_platform.c |  1 +
>  drivers/net/can/m_can/tcan4x5x-core.c  |  1 +
>  5 files changed, 21 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index b351597f594b..55df50580480 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -2392,7 +2392,15 @@ int m_can_class_suspend(struct device *dev)
>  	if (netif_running(ndev)) {
>  		netif_stop_queue(ndev);
>  		netif_device_detach(ndev);
> -		m_can_stop(ndev);
> +
> +		/* leave the chip running with rx interrupt enabled if it is
> +		 * used as a wake-up source.
> +		 */
> +		if (cdev->pm_wake_source)
> +			m_can_write(cdev, M_CAN_IE, IR_RF0N);
> +		else
> +			m_can_stop(ndev);
> +
>  		m_can_clk_stop(cdev);
>  	}
>  
> @@ -2419,11 +2427,15 @@ int m_can_class_resume(struct device *dev)
>  		ret = m_can_clk_start(cdev);
>  		if (ret)
>  			return ret;
> -		ret  = m_can_start(ndev);
> -		if (ret) {
> -			m_can_clk_stop(cdev);
>  
> -			return ret;
> +		if (cdev->pm_wake_source) {
> +			m_can_write(cdev, M_CAN_IE, cdev->active_interrupts);
> +		} else {
> +			ret  = m_can_start(ndev);

There is one space too much here.

> +			if (ret) {
> +				m_can_clk_stop(cdev);
> +				return ret;
> +			}
>  		}
>  
>  		netif_device_attach(ndev);
> diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
> index 2986c4ce0b2f..3a9edc292593 100644
> --- a/drivers/net/can/m_can/m_can.h
> +++ b/drivers/net/can/m_can/m_can.h
> @@ -97,6 +97,7 @@ struct m_can_classdev {
>  	u32 irqstatus;
>  
>  	int pm_clock_support;
> +	int pm_wake_source;

Can you avoid this new variable by using device_can_wakeup() and/or
device_may_wakeup() to check if the device is capable to wake up and if
wakeup is actually enabled?

Best,
Markus

>  	int is_peripheral;
>  
>  	// Cached M_CAN_IE register content
> diff --git a/drivers/net/can/m_can/m_can_pci.c b/drivers/net/can/m_can/m_can_pci.c
> index f2219aa2824b..45400de4163d 100644
> --- a/drivers/net/can/m_can/m_can_pci.c
> +++ b/drivers/net/can/m_can/m_can_pci.c
> @@ -125,6 +125,7 @@ static int m_can_pci_probe(struct pci_dev *pci, const struct pci_device_id *id)
>  	mcan_class->dev = &pci->dev;
>  	mcan_class->net->irq = pci_irq_vector(pci, 0);
>  	mcan_class->pm_clock_support = 1;
> +	mcan_class->pm_wake_source = 0;
>  	mcan_class->can.clock.freq = id->driver_data;
>  	mcan_class->ops = &m_can_pci_ops;
>  
> diff --git a/drivers/net/can/m_can/m_can_platform.c b/drivers/net/can/m_can/m_can_platform.c
> index ab1b8211a61c..df0367124b4c 100644
> --- a/drivers/net/can/m_can/m_can_platform.c
> +++ b/drivers/net/can/m_can/m_can_platform.c
> @@ -139,6 +139,7 @@ static int m_can_plat_probe(struct platform_device *pdev)
>  
>  	mcan_class->net->irq = irq;
>  	mcan_class->pm_clock_support = 1;
> +	mcan_class->pm_wake_source = 0;
>  	mcan_class->can.clock.freq = clk_get_rate(mcan_class->cclk);
>  	mcan_class->dev = &pdev->dev;
>  	mcan_class->transceiver = transceiver;
> diff --git a/drivers/net/can/m_can/tcan4x5x-core.c b/drivers/net/can/m_can/tcan4x5x-core.c
> index 8a4143809d33..870ab4aef610 100644
> --- a/drivers/net/can/m_can/tcan4x5x-core.c
> +++ b/drivers/net/can/m_can/tcan4x5x-core.c
> @@ -411,6 +411,7 @@ static int tcan4x5x_can_probe(struct spi_device *spi)
>  	priv->spi = spi;
>  
>  	mcan_class->pm_clock_support = 0;
> +	mcan_class->pm_wake_source = 0;
>  	mcan_class->can.clock.freq = freq;
>  	mcan_class->dev = &spi->dev;
>  	mcan_class->ops = &tcan4x5x_ops;
> -- 
> 2.42.0
>