The module parameter rx_packet_max can be overridden at module load or
boot args. But it doesn't adjust the max_mtu for the device accordingly.
If a CPSW device is to be used in a DSA architecture, increasing the
MTU by small amounts to account for switch overhead becomes necessary.
This way, a boot arg of cpsw.rx_packet_max=1600 should allow the MTU
to be increased to values of 1520, which is necessary for DSA tagging
protocols like "ocelot" and "seville".
Signed-off-by: Colin Foster <colin.foster@xxxxxxxxxxxxxxxx>
---
drivers/net/ethernet/ti/cpsw.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
index c0cd7de88316..d400163c4ef2 100644
--- a/drivers/net/ethernet/ti/cpsw.c
+++ b/drivers/net/ethernet/ti/cpsw.c
@@ -1625,6 +1625,14 @@ static int cpsw_probe(struct platform_device *pdev)
goto clean_cpts;
}
+ /* adjust max_mtu to match module parameter rx_packet_max */
+ if (cpsw->rx_packet_max > CPSW_MAX_PACKET_SIZE) {
+ ndev->max_mtu = ETH_DATA_LEN + (cpsw->rx_packet_max -
+ CPSW_MAX_PACKET_SIZE);
+ dev_info(dev, "overriding default MTU to %d\n\n",
+ ndev->max_mtu);
+ }
+
priv = netdev_priv(ndev);
priv->cpsw = cpsw;
priv->ndev = ndev;
--
2.25.1
