Subject: Re: [PATCH net-next v4 4/4] net: dsa: yt921x: Add port qdisc tbf support

From: Jakub Kicinski <[email-masked]>
Date: Mon, 13 Apr 2026 15:32:48 -0700

On Fri, 10 Apr 2026 01:12:04 +0800 David Yang wrote:
> +static int
> +yt921x_tbf_validate(struct yt921x_priv *priv,
> +		    const struct tc_tbf_qopt_offload *qopt, int *queuep)
> +{
> +	struct device *dev = to_device(priv);
> +	int queue = -1;
> +
> +	/* TODO: queue support */
> +	if (qopt->parent != TC_H_ROOT) {
> +		dev_err(dev, "Parent should be \"root\"\n");

Let's add extack to the offload struct like htb does and report this to
the user instead of the logs?

> +		return -EOPNOTSUPP;
> +	}
> +
> +	switch (qopt->command) {
> +	case TC_TBF_REPLACE: {
> +		const struct tc_tbf_qopt_offload_replace_params *p;
> +
> +		p = &qopt->replace_params;
> +
> +		if (!p->rate.mpu) {
> +			dev_info(dev, "Assuming you want mpu = 64\n");

BTW we can use extack for "warnings" like this, too

> +		} else if (p->rate.mpu != 64) {
> +			dev_err(dev, "mpu other than 64 not supported\n");
> +			return -EINVAL;
> +		}
> +		break;
> +	}
> +	default:
> +		break;
> +	}
> +
> +	*queuep = queue;
> +	return 0;
> +}
> +
> +static int
> +yt921x_dsa_port_setup_tc_tbf_port(struct dsa_switch *ds, int port,
> +				  const struct tc_tbf_qopt_offload *qopt)
> +{
> +	struct yt921x_priv *priv = to_yt921x_priv(ds);
> +	u32 ctrls[2];
> +	int res;
> +
> +	switch (qopt->command) {
> +	case TC_TBF_DESTROY:
> +		ctrls[0] = 0;
> +		ctrls[1] = 0;
> +		break;
> +	case TC_TBF_REPLACE: {
> +		const struct tc_tbf_qopt_offload_replace_params *p;
> +		struct yt921x_marker marker;
> +		u64 burst;
> +
> +		p = &qopt->replace_params;
> +
> +		/* where is burst??? */

Why not add it?

> +		burst = div_u64(priv->port_shape_slot_ns * p->rate.rate_bytes_ps,
> +				1000000000) + 10000;
-- 
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