Re: [PATCH net 06/12] net: systemport: Fix RUNT MIB counter register offset calculation

[Nicolai Buchwitz]

On 22.9.2026 01:12, Florian Fainelli wrote:
> In UniMAC hardware, there is a 0xC byte gap between the RX MIB counters
> and the TX MIB counters, and a second 0xC byte gap between the TX MIB
> counters and the RX RUNT MIB counters.
>
> In bcm_sysport_update_mib_counters(), 'offset' was only set to
> UMAC_MIB_STAT_OFFSET (0xC) for all non-RX counters, omitting the second
> 0xC gap for BCM_SYSPORT_STAT_RUNT counters. As a result, all 4 RUNT MIB
> counters were read from unmapped gap register space.
>
> Fix this by setting offset to 2 * UMAC_MIB_STAT_OFFSET (0x18) when
> reading BCM_SYSPORT_STAT_RUNT counters.
>
> 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 | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c 
> b/drivers/net/ethernet/broadcom/bcmsysport.c
> index 7f2e5e4efb8d..b69833d34bd5 100644
> --- a/drivers/net/ethernet/broadcom/bcmsysport.c
> +++ b/drivers/net/ethernet/broadcom/bcmsysport.c
> @@ -391,8 +391,10 @@ static void bcm_sysport_update_mib_counters(struct 
> bcm_sysport_priv *priv)
>  			if (priv->is_lite)
>  				continue;
>
> -			if (s->type != BCM_SYSPORT_STAT_MIB_RX)
> +			if (s->type == BCM_SYSPORT_STAT_MIB_TX)
>  				offset = UMAC_MIB_STAT_OFFSET;
> +			else if (s->type == BCM_SYSPORT_STAT_RUNT)
> +				offset = 2 * UMAC_MIB_STAT_OFFSET;
>  			val = umac_readl(priv, UMAC_MIB_START + j + offset);
>  			break;
>  		case BCM_SYSPORT_STAT_RXCHK

Reviewed-by: Nicolai Buchwitz <nb@xxxxxxxxxxx>

Thanks,
Nicolai