Re: [PATCH V2 1/5] net: can: flexcan: provide propper return code in ISR

[Varka Bhadram <varkabhadram@gmail.com>]

On 07/28/2014 12:04 PM, Matthias Klein wrote:
> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>
> flexcan_irq() always returns IRQ_HANDLED no matter if it actually did
> something or not. If the CAN interface is brought up without BERR
> reporting on a SoC which has the FLEXCAN_HAS_BROKEN_ERR_STATE feature
> then ERR reporting is activated but not really handled. That means on an
> open bus one receives a lot of STF_ERR and the only thing that happens
> is that the number of interrupts is incremented.
> This patch ensures that in such a case the core has a chance to detect
> such (or similar) misbehavior and disable the interrupt line.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Matthias Klein <matthias.klein@optimeas.de>
> ---
>   drivers/net/can/flexcan.c | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> index e381142..f677b49 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -641,6 +641,7 @@ static irqreturn_t flexcan_irq(int irq, void *dev_id)
>   	struct flexcan_priv *priv = netdev_priv(dev);
>   	struct flexcan_regs __iomem *regs = priv->base;
>   	u32 reg_iflag1, reg_esr;
> +	int worked = 0;

bool instead if int ...?

>   
>   	reg_iflag1 = flexcan_read(&regs->iflag1);
>   	reg_esr = flexcan_read(&regs->esr);
> @@ -667,6 +668,7 @@ static irqreturn_t flexcan_irq(int irq, void *dev_id)
>   		flexcan_write(priv->reg_ctrl_default & ~FLEXCAN_CTRL_ERR_ALL,
>   		       &regs->ctrl);
>   		napi_schedule(&priv->napi);
> +		worked = 1;
>   	}
>   
>   	/* FIFO overflow */
> @@ -674,6 +676,7 @@ static irqreturn_t flexcan_irq(int irq, void *dev_id)
>   		flexcan_write(FLEXCAN_IFLAG_RX_FIFO_OVERFLOW, &regs->iflag1);
>   		dev->stats.rx_over_errors++;
>   		dev->stats.rx_errors++;
> +		worked = 1;
>   	}
>   
>   	/* transmission complete interrupt */
> @@ -683,9 +686,12 @@ static irqreturn_t flexcan_irq(int irq, void *dev_id)
>   		can_led_event(dev, CAN_LED_EVENT_TX);
>   		flexcan_write((1 << FLEXCAN_TX_BUF_ID), &regs->iflag1);
>   		netif_wake_queue(dev);
> +		worked = 1;
>   	}
> -
> -	return IRQ_HANDLED;
> +	if (worked)
> +		return IRQ_HANDLED;
> +	else
> +		return IRQ_NONE;
>   }
>   
>   static void flexcan_set_bittiming(struct net_device *dev)


-- 
Regards,
Varka Bhadram.