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

[Florian Fainelli <florian.fainelli@broadcom.com>]

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@broadcom.com>
---
 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:
-- 
2.34.1