On 10/4/19 11:02 AM, Anssi Hannula wrote:
> Userspace can signal with CAN_CTRLMODE_BERR_REPORTING whether they need
> reporting of bus errors (CAN_ERR_BUSERROR) or not.
>
> However, xilinx_can driver currently always sends CAN_ERR_BUSERROR
> frames to userspace on bus errors.
>
> To improve performance on error conditions when bus error reporting is
> not needed, avoid sending CAN_ERR_BUSERROR frames unless requested via
> CAN_CTRLMODE_BERR_REPORTING.
>
> The error interrupt is still kept enabled as there is no dedicated state
> transition interrupt, but just disabling error frame submission still
> yields a significant performance improvement. In a simple test with
> continuous bus errors and no userspace programs reading/writing CAN I
> saw system CPU load reduced by 1/3.
>
> Tested on a ZynqMP board with CAN-FD v1.0.
>
> Signed-off-by: Anssi Hannula <anssi.hannula@xxxxxxxxxx>
> ---
> drivers/net/can/xilinx_can.c | 84 +++++++++++++++++++-----------------
> 1 file changed, 45 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
> index 911b34316c9d..9b9ec07f7e5b 100644
> --- a/drivers/net/can/xilinx_can.c
> +++ b/drivers/net/can/xilinx_can.c
> @@ -471,6 +471,10 @@ static int xcan_chip_start(struct net_device *ndev)
> return err;
>
> /* Enable interrupts */
> + /* We enable the ERROR interrupt even with CAN_CTRLMODE_BERR_REPORTING
> + * disabled as there is no dedicated interrupt for a state change to
> + * ERROR_WARNING/ERROR_PASSIVE.
> + */
> ier = XCAN_IXR_TXOK_MASK | XCAN_IXR_BSOFF_MASK |
> XCAN_IXR_WKUP_MASK | XCAN_IXR_SLP_MASK |
> XCAN_IXR_ERROR_MASK | XCAN_IXR_RXOFLW_MASK |
> @@ -981,11 +985,10 @@ static void xcan_err_interrupt(struct net_device *ndev, u32 isr)
> {
> struct xcan_priv *priv = netdev_priv(ndev);
> struct net_device_stats *stats = &ndev->stats;
> - struct can_frame *cf;
> - struct sk_buff *skb;
> + struct can_frame cf;
> u32 err_status;
>
> - skb = alloc_can_err_skb(ndev, &cf);
> + memset(&cf, 0, sizeof(cf));
This change is unrelated to the one described. Please move these into a
seperate patch.
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
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