Subject: Re: [PATCH v3 10/16] can: m_can: Add tx coalescing ethtool support

From: Simon Horman <[email-masked]>
Date: Thu, 16 Mar 2023 11:06:58 +0100

On Wed, Mar 15, 2023 at 12:05:40PM +0100, Markus Schneider-Pargmann wrote:
> Add get/set functions for ethtool coalescing. tx-frames-irq and
> tx-usecs-irq can only be set/unset together. tx-frames-irq needs to be
> less than TXE and TXB.

Perhaps I'm reading this wrong (maybe I need a coffee). But I think it
might be a bit clearer to call out the TX aspect of this patch up front (I
know it is in the subject.

Maybe something like this:

  Add TX support to get/set functions for ethtool coalescing...

> 
> As rx and tx share the same timer, rx-usecs-irq and tx-usecs-irq can be
> enabled/disabled individually but they need to have the same value if
> enabled.
> 
> Signed-off-by: Markus Schneider-Pargmann <[email-masked]>

Nits above and below not withstanding,

Reviewed-by: Simon Horman <[email-masked]>

> ---
>  drivers/net/can/m_can/m_can.c | 38 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 37 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 7f8decfae81e..4e794166664a 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -1945,6 +1945,8 @@ static int m_can_get_coalesce(struct net_device *dev,
>  
>  	ec->rx_max_coalesced_frames_irq = cdev->rx_max_coalesced_frames_irq;
>  	ec->rx_coalesce_usecs_irq = cdev->rx_coalesce_usecs_irq;
> +	ec->tx_max_coalesced_frames_irq = cdev->tx_max_coalesced_frames_irq;
> +	ec->tx_coalesce_usecs_irq = cdev->tx_coalesce_usecs_irq;
>  
>  	return 0;
>  }
> @@ -1971,16 +1973,50 @@ static int m_can_set_coalesce(struct net_device *dev,
>  		netdev_err(dev, "rx-frames-irq and rx-usecs-irq can only be set together\n");
>  		return -EINVAL;
>  	}
> +	if (ec->tx_max_coalesced_frames_irq > cdev->mcfg[MRAM_TXE].num) {
> +		netdev_err(dev, "tx-frames-irq %u greater than the TX event FIFO %u\n",
> +			   ec->tx_max_coalesced_frames_irq,
> +			   cdev->mcfg[MRAM_TXE].num);
> +		return -EINVAL;
> +	}
> +	if (ec->tx_max_coalesced_frames_irq > cdev->mcfg[MRAM_TXB].num) {
> +		netdev_err(dev, "tx-frames-irq %u greater than the TX FIFO %u\n",
> +			   ec->tx_max_coalesced_frames_irq,
> +			   cdev->mcfg[MRAM_TXB].num);
> +		return -EINVAL;
> +	}
> +	if ((ec->tx_max_coalesced_frames_irq == 0) != (ec->tx_coalesce_usecs_irq == 0)) {
> +		netdev_err(dev, "tx-frames-irq and tx-usecs-irq can only be set together\n");
> +		return -EINVAL;
> +	}

nit: checkpatch complains about unnecessary parentheses

drivers/net/can/m_can/m_can.c:1988: CHECK: Unnecessary parentheses around 'ec->tx_max_coalesced_frames_irq == 0'
+	if ((ec->tx_max_coalesced_frames_irq == 0) != (ec->tx_coalesce_usecs_irq == 0)) {

drivers/net/can/m_can/m_can.c:1988: CHECK: Unnecessary parentheses around 'ec->tx_coalesce_usecs_irq == 0'
+	if ((ec->tx_max_coalesced_frames_irq == 0) != (ec->tx_coalesce_usecs_irq == 0)) {

> +	if (ec->rx_coalesce_usecs_irq != 0 && ec->tx_coalesce_usecs_irq != 0 &&
> +	    ec->rx_coalesce_usecs_irq != ec->tx_coalesce_usecs_irq) {
> +		netdev_err(dev, "rx-usecs-irq %u needs to be equal to tx-usecs-irq %u if both are enabled\n",
> +			   ec->rx_coalesce_usecs_irq,
> +			   ec->tx_coalesce_usecs_irq);
> +		return -EINVAL;
> +	}
>  
>  	cdev->rx_max_coalesced_frames_irq = ec->rx_max_coalesced_frames_irq;
>  	cdev->rx_coalesce_usecs_irq = ec->rx_coalesce_usecs_irq;
> +	cdev->tx_max_coalesced_frames_irq = ec->tx_max_coalesced_frames_irq;
> +	cdev->tx_coalesce_usecs_irq = ec->tx_coalesce_usecs_irq;
> +
> +	if (cdev->rx_coalesce_usecs_irq)
> +		cdev->irq_timer_wait =
> +			ns_to_ktime(cdev->rx_coalesce_usecs_irq * NSEC_PER_USEC);
> +	else
> +		cdev->irq_timer_wait =
> +			ns_to_ktime(cdev->tx_coalesce_usecs_irq * NSEC_PER_USEC);

nit: perhaps adding us_to_ktime() and using it treewide would be interesting

>  	return 0;
>  }
>  
>  static const struct ethtool_ops m_can_ethtool_ops = {
>  	.supported_coalesce_params = ETHTOOL_COALESCE_RX_USECS_IRQ |
> -		ETHTOOL_COALESCE_RX_MAX_FRAMES_IRQ,
> +		ETHTOOL_COALESCE_RX_MAX_FRAMES_IRQ |
> +		ETHTOOL_COALESCE_TX_USECS_IRQ |
> +		ETHTOOL_COALESCE_TX_MAX_FRAMES_IRQ,
>  	.get_ts_info = ethtool_op_get_ts_info,
>  	.get_coalesce = m_can_get_coalesce,
>  	.set_coalesce = m_can_set_coalesce,
> -- 
> 2.39.2
>