Re: [PATCH net 11/12] net: systemport: Update TDMA queue mapping dynamically on changeupper

[Nicolai Buchwitz]

Hi Florian

On 22.9.2026 01:13, Florian Fainelli wrote:
> When DSA upper devices are dynamically attached or detached while the
> master SYSTEMPORT interface is already up and running 
> (netif_running()),
> bcm_sysport_map_queues() and bcm_sysport_unmap_queues() updated the
> internal software mappings but did not update the 
> TDMA_DESC_RING_MAPPING
> hardware registers, because programming was previously deferred until
> bcm_sysport_init_tx_ring().
>
> Update TDMA_DESC_RING_MAPPING registers immediately if netif_running()
> is true during map_queues and unmap_queues.
>
> Fixes: 1593cd40d785 ("net: systemport: use standard netdevice notifier 
> to detect DSA presence")
> Assisted-by: LLM
> Signed-off-by: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>
> ---
>  drivers/net/ethernet/broadcom/bcmsysport.c | 23 +++++++++++++++++++---
>  1 file changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c 
> b/drivers/net/ethernet/broadcom/bcmsysport.c
> index dd5a7c9dd90f..e5bb7fa84fda 100644
> --- a/drivers/net/ethernet/broadcom/bcmsysport.c
> +++ b/drivers/net/ethernet/broadcom/bcmsysport.c

> [...]

> @@ -2390,6 +2399,14 @@ static int bcm_sysport_unmap_queues(struct 
> net_device *dev,
>  		qp = ring->switch_queue;
>  		if (qp + port * num_tx_queues < ARRAY_SIZE(priv->ring_map))
>  			priv->ring_map[qp + port * num_tx_queues] = NULL;
> +
> +		if (netif_running(dev)) {
> +			reg = tdma_readl(priv, TDMA_DESC_RING_MAPPING(q));
> +			reg &= ~(RING_QID_MASK |
> +				 RING_PORT_ID_MASK << RING_PORT_ID_SHIFT);
> +			reg |= RING_IGNORE_STATUS;
> +			tdma_writel(priv, reg, TDMA_DESC_RING_MAPPING(q));
> +		}

RING_IGNORE_STATUS is never cleared in init_tx_rings(), so

    echo <sf2-node> > /sys/bus/platform/drivers/brcm-sf2/unbind
    ip link set eth0 down
    echo <sf2-node> > /sys/bus/platform/drivers/brcm-sf2/bind
    ip link set eth0 up

keeps the bit set from unmap. Clear it in init_tx_ring() too?

> [...]

Thanks,
Nicolai