netdev - RE: [PATCH v3] can: m_can: add support for handling arbitration error

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Date:   Wed, 6 Nov 2019 11:29:24 +0530
From:   "pankj.sharma" <pankj.sharma@...sung.com>
To:     <mkl@...gutronix.de>, <wg@...ndegger.com>
Cc:     <davem@...emloft.net>, <pankaj.dubey@...sung.com>,
        <rcsekar@...sung.com>, <jhofstee@...tronenergy.com>,
        <simon.horman@...ronome.com>,
        "'Sriram Dash'" <sriram.dash@...sung.com>,
        <linux-can@...r.kernel.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3] can: m_can: add support for handling arbitration
 error

Gentle Ping!

> From: Pankaj Sharma <pankj.sharma@...sung.com>
> Subject: [PATCH v3] can: m_can: add support for handling arbitration error
> 
> The Bosch MCAN hardware (3.1.0 and above) supports interrupt flag to detect
> Protocol error in arbitration phase.
> 
> Transmit error statistics is currently not updated from the MCAN driver.
> Protocol error in arbitration phase is a TX error and the network statistics should
> be updated accordingly.
> 
> The member "tx_error" of "struct net_device_stats" should be incremented as
> arbitration is a transmit protocol error. Also "arbitration_lost" of "struct
> can_device_stats" should be incremented to report arbitration lost.
> 
> Signed-off-by: Pankaj Sharma <pankj.sharma@...sung.com>
> Signed-off-by: Sriram Dash <sriram.dash@...sung.com>
> ---
> 
> changes in v3:
> - handle arbitration lost stats even if the allocation of the skb fails
> 
> changes in v2:
> - common m_can_ prefix for is_protocol_err function
> - handling stats even if the allocation of the skb fails
> - resolving build errors on net-next branch
> 
>  drivers/net/can/m_can/m_can.c | 42
> +++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 75e7490c4299..02c5795b7393 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -778,6 +778,43 @@ static inline bool is_lec_err(u32 psr)
>  	return psr && (psr != LEC_UNUSED);
>  }
> 
> +static inline bool m_can_is_protocol_err(u32 irqstatus) {
> +	return irqstatus & IR_ERR_LEC_31X;
> +}
> +
> +static int m_can_handle_protocol_error(struct net_device *dev, u32
> +irqstatus) {
> +	struct net_device_stats *stats = &dev->stats;
> +	struct m_can_classdev *cdev = netdev_priv(dev);
> +	struct can_frame *cf;
> +	struct sk_buff *skb;
> +
> +	/* propagate the error condition to the CAN stack */
> +	skb = alloc_can_err_skb(dev, &cf);
> +
> +	/* update tx error stats since there is protocol error */
> +	stats->tx_errors++;
> +
> +	/* update arbitration lost status */
> +	if (cdev->version >= 31 && (irqstatus & IR_PEA)) {
> +		netdev_dbg(dev, "Protocol error in Arbitration fail\n");
> +		cdev->can.can_stats.arbitration_lost++;
> +		if (skb) {
> +			cf->can_id |= CAN_ERR_LOSTARB;
> +			cf->data[0] |= CAN_ERR_LOSTARB_UNSPEC;
> +		}
> +	}
> +
> +	if (unlikely(!skb)) {
> +		netdev_dbg(dev, "allocation of skb failed\n");
> +		return 0;
> +	}
> +	netif_receive_skb(skb);
> +
> +	return 1;
> +}
> +
>  static int m_can_handle_bus_errors(struct net_device *dev, u32 irqstatus,
>  				   u32 psr)
>  {
> @@ -792,6 +829,11 @@ static int m_can_handle_bus_errors(struct net_device
> *dev, u32 irqstatus,
>  	    is_lec_err(psr))
>  		work_done += m_can_handle_lec_err(dev, psr & LEC_UNUSED);
> 
> +	/* handle protocol errors in arbitration phase */
> +	if ((cdev->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING) &&
> +	    m_can_is_protocol_err(irqstatus))
> +		work_done += m_can_handle_protocol_error(dev, irqstatus);
> +
>  	/* other unproccessed error interrupts */
>  	m_can_handle_other_err(dev, irqstatus);
> 
> --
> 2.17.1