Re: [PATCH net-next v8 5/7] net: stmmac: support fp parameter of tc-mqprio

[Vladimir Oltean <olteanv@gmail.com>]

On Thu, Sep 05, 2024 at 03:02:26PM +0800, Furong Xu wrote:
> tc-mqprio can select whether traffic classes are express or preemptible.
> 
> After some traffic tests, MAC merge layer statistics are all good.
> 
> Local device:
> ethtool --include-statistics --json --show-mm eth1
> [ {
>         "ifname": "eth1",
>         "pmac-enabled": true,
>         "tx-enabled": true,
>         "tx-active": true,
>         "tx-min-frag-size": 60,
>         "rx-min-frag-size": 60,
>         "verify-enabled": true,
>         "verify-time": 100,
>         "max-verify-time": 128,
>         "verify-status": "SUCCEEDED",
>         "statistics": {
>             "MACMergeFrameAssErrorCount": 0,
>             "MACMergeFrameSmdErrorCount": 0,
>             "MACMergeFrameAssOkCount": 0,
>             "MACMergeFragCountRx": 0,
>             "MACMergeFragCountTx": 35105,
>             "MACMergeHoldCount": 0
>         }
>     } ]
> 
> Remote device:
> ethtool --include-statistics --json --show-mm end1
> [ {
>         "ifname": "end1",
>         "pmac-enabled": true,
>         "tx-enabled": true,
>         "tx-active": true,
>         "tx-min-frag-size": 60,
>         "rx-min-frag-size": 60,
>         "verify-enabled": true,
>         "verify-time": 100,
>         "max-verify-time": 128,
>         "verify-status": "SUCCEEDED",
>         "statistics": {
>             "MACMergeFrameAssErrorCount": 0,
>             "MACMergeFrameSmdErrorCount": 0,
>             "MACMergeFrameAssOkCount": 35105,
>             "MACMergeFragCountRx": 35105,
>             "MACMergeFragCountTx": 0,
>             "MACMergeHoldCount": 0
>         }
>     } ]
> 
> Tested on DWMAC CORE 5.10a
> 
> Signed-off-by: Furong Xu <0x1207@gmail.com>
> ---
> +int dwmac5_fpe_map_preemption_class(struct net_device *ndev,
> +				    struct netlink_ext_ack *extack, u32 pclass)
> +{
> +	u32 offset, count, val, preemptible_txqs = 0;
> +	struct stmmac_priv *priv = netdev_priv(ndev);
> +	u32 num_tc = ndev->num_tc;
> +
> +	if (!pclass)
> +		goto update_mapping;
> +
> +	/* DWMAC CORE4+ can not program TC:TXQ mapping to hardware.
> +	 *
> +	 * Synopsys Databook:
> +	 * "The number of Tx DMA channels is equal to the number of Tx queues,
> +	 * and is direct one-to-one mapping."
> +	 */
> +	for (u32 tc = 0; tc < num_tc; tc++) {
> +		count = ndev->tc_to_txq[tc].count;
> +		offset = ndev->tc_to_txq[tc].offset;
> +
> +		if (pclass & BIT(tc))
> +			preemptible_txqs |= GENMASK(offset + count - 1, offset);
> +
> +		/* This is 1:1 mapping, go to next TC */
> +		if (count == 1)
> +			continue;
> +
> +		if (priv->plat->tx_sched_algorithm == MTL_TX_ALGORITHM_SP) {
> +			NL_SET_ERR_MSG_MOD(extack, ALG_ERR_MSG);
> +			return -EINVAL;
> +		}
> +
> +		u32 queue_weight = priv->plat->tx_queues_cfg[offset].weight;

Please do not put variable declarations in the middle of the scope.
Declare "u32 queue_weight" separately and just keep the assignment here.

> +
> +		for (u32 i = 1; i < count; i++) {
> +			if (priv->plat->tx_queues_cfg[offset + i].weight !=
> +			    queue_weight) {
> +				NL_SET_ERR_MSG_FMT_MOD(extack, WEIGHT_ERR_MSG,
> +						       queue_weight, tc);
> +				return -EINVAL;
> +			}
> +		}
> +	}
> +
> +update_mapping:
> +	val = readl(priv->ioaddr + MTL_FPE_CTRL_STS);
> +	writel(u32_replace_bits(val, preemptible_txqs, DWMAC5_PREEMPTION_CLASS),
> +	       priv->ioaddr + MTL_FPE_CTRL_STS);
> +
> +	return 0;
> +}

Otherwise:

Reviewed-by: Vladimir Oltean <olteanv@gmail.com>