Re: [PATCH v7 net-next 13/15] net: dsa: netc: initialize buffer pool table and implement flow-control

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] NETC_PAUSE_THRESH is configured to 0xFF00, causing an excessively high rate of refresh PAUSE frames during congestion.
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commit c202728eb814feedb124fe98e802ff02c4f35dad
Author: Wei Fang <wei.fang@nxp.com>

net: dsa: netc: initialize buffer pool table and implement flow-control

This commit initializes the buffer pool table for the switch to implement
flow-control. It sets up IPV-to-buffer-pool mappings, enables TX/RX pause
frames, and programs the pause quanta and refresh thresholds.

> diff --git a/drivers/net/dsa/netc/netc_main.c b/drivers/net/dsa/netc/netc_main.c
> index 34b5e655d1c96..7a40648496939 100644
> --- a/drivers/net/dsa/netc/netc_main.c
> +++ b/drivers/net/dsa/netc/netc_main.c
[ ... ]
> @@ -403,6 +406,15 @@ static void netc_port_fixed_config(struct netc_port *np)
[ ... ]
> +	/* When a quanta timer counts down and reaches this value,
> +	 * the MAC sends a refresh PAUSE frame with the programmed
> +	 * full quanta value if a pause condition still exists.
> +	 */
> +	netc_mac_port_wr(np, NETC_PM_PAUSE_THRESH(0), NETC_PAUSE_THRESH);
[ ... ]
> diff --git a/drivers/net/dsa/netc/netc_switch.h b/drivers/net/dsa/netc/netc_switch.h
> index cc278a862623e..4a9bf69907e9c 100644
> --- a/drivers/net/dsa/netc/netc_switch.h
> +++ b/drivers/net/dsa/netc/netc_switch.h
[ ... ]
> @@ -28,11 +28,27 @@
[ ... ]
> +/* PAUSE quanta: 0xFFFF = 65535 quanta (each quanta = 512 bit times) */
> +#define NETC_PAUSE_QUANTA		0xFFFF
> +/* PAUSE refresh threshold: send refresh when timer reaches this value */
> +#define NETC_PAUSE_THRESH		0xFF00

Could NETC_PAUSE_THRESH be a typo for 0x00FF?

When the timer counts down from 0xFFFF and reaches 0xFF00, it has only
elapsed 255 quanta. At 1 Gbps, 255 quanta is approximately 130 us, which
means the switch will send a refresh PAUSE frame to the link partner every
130 us during congestion, rather than waiting for a typical half-interval.

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Sashiko AI review · https://sashiko.dev/#/patchset/20260513030454.1666570-1-wei.fang@nxp.com?part=13