Re: [PATCH net-next v2] net: mana: Add Interrupt Moderation support

[Paolo Abeni]

On 6/5/26 1:41 AM, Haiyang Zhang wrote:
> diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
> index db14357d3732..b1e0c444f414 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> @@ -1551,6 +1551,9 @@ int mana_create_wq_obj(struct mana_port_context *apc,
>  
>  	mana_gd_init_req_hdr(&req.hdr, MANA_CREATE_WQ_OBJ,
>  			     sizeof(req), sizeof(resp));
> +
> +	req.hdr.req.msg_version = GDMA_MESSAGE_V3;
> +	req.hdr.resp.msg_version = GDMA_MESSAGE_V2;

Sashiko noted the above cold break initialization on older firmware:

https://sashiko.dev/#/patchset/20260604234211.2056341-1-haiyangz%40linux.microsoft.com

[...]
> +static void mana_update_rx_dim(struct mana_cq *cq)
> +{
> +	struct mana_port_context *apc = netdev_priv(cq->rxq->ndev);
> +	struct mana_rxq *rxq = cq->rxq;
> +	struct dim_sample dim_sample = {};

Minor nit: please fix the variable declaration order above. Other
occurrences below.

[...]
> @@ -440,17 +474,94 @@ static int mana_set_coalesce(struct net_device *ndev,
>  		return -EINVAL;
>  	}
>  
> -	saved_cqe_coalescing_enable = apc->cqe_coalescing_enable;
> +	if (ec->rx_coalesce_usecs > MANA_INTR_MODR_USEC_MAX ||
> +	    ec->tx_coalesce_usecs > MANA_INTR_MODR_USEC_MAX) {
> +		NL_SET_ERR_MSG_FMT(extack,
> +				   "coalesce usecs must be <= %lu",
> +				   MANA_INTR_MODR_USEC_MAX);
> +		return -EINVAL;
> +	}
> +
> +	if (ec->rx_max_coalesced_frames > MANA_INTR_MODR_COMP_MAX ||
> +	    ec->tx_max_coalesced_frames > MANA_INTR_MODR_COMP_MAX) {
> +		NL_SET_ERR_MSG_FMT(extack,
> +				   "coalesce frames must be <= %lu",
> +				   MANA_INTR_MODR_COMP_MAX);
> +		return -EINVAL;
> +	}
> +
> +	if (ec->rx_coalesce_usecs != apc->intr_modr_rx_usec ||
> +	    ec->rx_max_coalesced_frames != apc->intr_modr_rx_comp ||
> +	    ec->tx_coalesce_usecs != apc->intr_modr_tx_usec ||
> +	    ec->tx_max_coalesced_frames != apc->intr_modr_tx_comp)
> +		modr_changed = true;
> +
> +	saved.intr_modr_rx_usec = apc->intr_modr_rx_usec;
> +	saved.intr_modr_rx_comp = apc->intr_modr_rx_comp;
> +	saved.intr_modr_tx_usec = apc->intr_modr_tx_usec;
> +	saved.intr_modr_tx_comp = apc->intr_modr_tx_comp;
> +
> +	apc->intr_modr_rx_usec = ec->rx_coalesce_usecs;
> +	apc->intr_modr_rx_comp = ec->rx_max_coalesced_frames;
> +	apc->intr_modr_tx_usec = ec->tx_coalesce_usecs;
> +	apc->intr_modr_tx_comp = ec->tx_max_coalesced_frames;
> +
> +	if (!!ec->use_adaptive_rx_coalesce != apc->rx_dim_enabled ||
> +	    !!ec->use_adaptive_tx_coalesce != apc->tx_dim_enabled)
> +		dim_changed = true;
> +
> +	saved.rx_dim_enabled = apc->rx_dim_enabled;
> +	saved.tx_dim_enabled = apc->tx_dim_enabled;
> +	apc->rx_dim_enabled = !!ec->use_adaptive_rx_coalesce;
> +	apc->tx_dim_enabled = !!ec->use_adaptive_tx_coalesce;
> +
> +	saved.cqe_coalescing_enable = apc->cqe_coalescing_enable;
>  	apc->cqe_coalescing_enable =
>  		kernel_coal->rx_cqe_frames == MANA_RXCOMP_OOB_NUM_PPI;
>  
>  	if (!apc->port_is_up)
>  		return 0;
>  
> -	err = mana_config_rss(apc, TRI_STATE_TRUE, false, false);
> -	if (err)
> -		apc->cqe_coalescing_enable = saved_cqe_coalescing_enable;
> +	if (apc->cqe_coalescing_enable != saved.cqe_coalescing_enable &&
> +	    !modr_changed && !dim_changed) {
> +		/* If only CQE coalescing setting is changed, we can just update
> +		 * RSS configuration.
> +		 */
> +		err = mana_config_rss(apc, TRI_STATE_TRUE, false, false);
> +		if (err) {
> +			netdev_err(ndev, "Change CQE coalescing failed: %d\n",
> +				   err);
> +			apc->cqe_coalescing_enable =
> +				saved.cqe_coalescing_enable;
> +			return err;
> +		}
> +		return 0;
> +	}
> +
> +	if (modr_changed || dim_changed) {
> +		err = mana_detach(ndev, false);
> +		if (err) {
> +			netdev_err(ndev, "mana_detach failed: %d\n", err);
> +			goto restore_modr;
> +		}
> +
> +		err = mana_attach(ndev);
> +		if (err) {
> +			netdev_err(ndev, "mana_attach failed: %d\n", err);
> +			goto restore_modr;
> +		}

You should try hard to avoid this sequence: if mana_attach fails,
mana_set_coalesce() will leave the NIC unexpectedly down.

/P