Re: [PATCH 5/6] can: janz-ican3: avoid firmware lockup caused by infinite bus error quota

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 07/19/2012 12:33 AM, Ira W. Snyder wrote:
> From: "Ira W. Snyder" <iws@ovro.caltech.edu>
> 
> If the bus error quota is set to infinite and the host CPU cannot keep
> up, the Janz VMOD-ICAN3 firmware will stop responding to control
> messages until the controller is reset.
> 
> The firmware will automatically stop sending bus error messages when the
> quota is reached, and will only resume sending bus error messages when
> the quota is re-set to a positive value.
> 
> This limitation is worked around by setting the bus error quota to one
> message, and then re-setting the quota to one message every time a bus
> error message is received. By doing this, the firmware never stops
> responding to control messages. The CAN bus can be reset without a
> hard-reset of the controller card.
> 
> Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>

looks good.

Marc
> ---
>  drivers/net/can/janz-ican3.c |   13 ++++++++++++-
>  1 files changed, 12 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/net/can/janz-ican3.c b/drivers/net/can/janz-ican3.c
> index 1304712..df3ba07 100644
> --- a/drivers/net/can/janz-ican3.c
> +++ b/drivers/net/can/janz-ican3.c
> @@ -960,6 +960,7 @@ static int ican3_handle_cevtind(struct ican3_dev *mod, struct ican3_msg *msg)
>  	 * skb allocation when it will just be freed immediately.
>  	 */
>  	if (isrc == CEVTIND_BEI) {
> +		int ret;
>  		dev_dbg(mod->dev, "bus error interrupt, part 1\n");
>  
>  		/* TX error */
> @@ -970,6 +971,16 @@ static int ican3_handle_cevtind(struct ican3_dev *mod, struct ican3_msg *msg)
>  			stats->rx_errors++;
>  		}
>  
> +		/*
> +		 * The controller automatically disables bus-error interrupts
> +		 * and therefore we must re-enable them.
> +		 */
> +		ret = ican3_set_buserror(mod, 1);
> +		if (ret) {
> +			dev_err(mod->dev, "unable to re-enable bus-error\n");
> +			return ret;
> +		}
> +
>  		/* bus error reporting is off, return immediately */
>  		if (!(mod->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING))
>  			return 0;
> @@ -1447,7 +1458,7 @@ static int __devinit ican3_startup_module(struct ican3_dev *mod)
>  	}
>  
>  	/* default to "bus errors enabled" */
> -	ret = ican3_set_buserror(mod, ICAN3_BUSERR_QUOTA_MAX);
> +	ret = ican3_set_buserror(mod, 1);
>  	if (ret) {
>  		dev_err(mod->dev, "unable to set bus-error\n");
>  		return ret;


-- 
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