Re: [PATCH net 12/12] net: systemport: Complete resource teardown even on DMA disable timeout

[Nicolai Buchwitz]

Hi Florian

On 22.9.2026 01:13, Florian Fainelli wrote:
> In bcm_sysport_stop(), if tdma_enable_set() or rdma_enable_set() timed
> out, the function returned early with an error code. However, 
> ndo_stop()
> callers in the networking core ignore error returns, leaving the
> software ring structures allocated, interrupts registered, PHY
> connected, and clock enabled. If the interface was subsequently brought
> up again, request_irq() and PHY connection would fail or leak.
>
> Ensure all software ring teardown, interrupt freeing, PHY
> disconnection, and clock disabling steps are executed regardless of DMA
> disable timeouts.
>
> Fixes: 80105befdb4b ("net: systemport: add Broadcom SYSTEMPORT Ethernet 
> MAC driver")
> Assisted-by: LLM
> Signed-off-by: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>
> ---
>  drivers/net/ethernet/broadcom/bcmsysport.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c 
> b/drivers/net/ethernet/broadcom/bcmsysport.c
> index e5bb7fa84fda..2b064da4eb7c 100644
> --- a/drivers/net/ethernet/broadcom/bcmsysport.c
> +++ b/drivers/net/ethernet/broadcom/bcmsysport.c
> @@ -2088,19 +2088,15 @@ static int bcm_sysport_stop(struct net_device 
> *dev)
>  	umac_enable_set(priv, CMD_RX_EN, 0);
>
>  	ret = tdma_enable_set(priv, 0);
> -	if (ret) {
> +	if (ret)
>  		netdev_err(dev, "timeout disabling TDMA\n");
> -		return ret;
> -	}
>
>  	/* Wait for a maximum packet size to be drained */
>  	usleep_range(2000, 3000);
>
>  	ret = rdma_enable_set(priv, 0);
> -	if (ret) {
> +	if (ret)
>  		netdev_err(dev, "timeout disabling RDMA\n");
> -		return ret;
> -	}

If TDMA or RDMA don't stop, the rings get freed while the hardware may
still use them. Maybe topctrl_flush() before freeing?

The same pattern would probably apply to bcm_sysport_suspend().

> [...]

Thanks,
Nicolai