netdev - Re: [PATCH] can: mcan: Add support for handling dlec error on CAN FD format frame

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Date:   Wed, 12 Oct 2022 09:47:19 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Vivek Yadav <vivek.2311@...sung.com>
Cc:     rcsekar@...sung.com, wg@...ndegger.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        pankaj.dubey@...sung.com, linux-can@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] can: mcan: Add support for handling dlec error on CAN FD
 format frame

On 11.10.2022 17:05:12, Vivek Yadav wrote:
> When a frame in CAN FD format has reached the data phase, the next
> CAN event (error or valid frame) will be shown in DLEC.
> 
> Utilizes the dedicated flag (Data Phase Last Error Code: DLEC flag) to
> determine the type of last error that occurred in the data phase
> of a CAN FD frame and handle the bus errors.
> 
> Signed-off-by: Vivek Yadav <vivek.2311@...sung.com>

I've just sent patch

| https://lore.kernel.org/all/20221012074205.691384-1-mkl@pengutronix.de

to clean up the LEC error handling a bit. This makes it easier to add
DLEC support.

> ---
>  drivers/net/can/m_can/m_can.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 4709c012b1dc..c070580d35fb 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -156,6 +156,7 @@ enum m_can_reg {
>  #define PSR_EW		BIT(6)
>  #define PSR_EP		BIT(5)
>  #define PSR_LEC_MASK	GENMASK(2, 0)
> +#define PSR_DLEC_SHIFT  8

Please define a PSR_DLEC_MASK and follow the lec handling in my patch.

regards,
Marc

>  
>  /* Interrupt Register (IR) */
>  #define IR_ALL_INT	0xffffffff
> @@ -870,6 +871,7 @@ static int m_can_handle_bus_errors(struct net_device *dev, u32 irqstatus,
>  {
>  	struct m_can_classdev *cdev = netdev_priv(dev);
>  	int work_done = 0;
> +	int dpsr = 0;
>  
>  	if (irqstatus & IR_RF0L)
>  		work_done += m_can_handle_lost_msg(dev);
> @@ -884,6 +886,15 @@ static int m_can_handle_bus_errors(struct net_device *dev, u32 irqstatus,
>  	    m_can_is_protocol_err(irqstatus))
>  		work_done += m_can_handle_protocol_error(dev, irqstatus);
>  
> +	if (cdev->can.ctrlmode & CAN_CTRLMODE_FD) {

I think we can skip the check for CAN-FD here.

> +		dpsr  = psr >> PSR_DLEC_SHIFT;
> +		if ((cdev->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING) &&
> +		    is_lec_err(dpsr)) {
> +			netdev_dbg(dev, "Data phase error detected\n");
> +			work_done += m_can_handle_lec_err(dev, dpsr & LEC_UNUSED);
> +		}
> +	}
> +
>  	/* other unproccessed error interrupts */
>  	m_can_handle_other_err(dev, irqstatus);

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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