diff mbox series

[net,1/3] net: lan966x: Fix the MTU calculation

Message ID 20221023184838.4128061-2-horatiu.vultur@microchip.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series net: lan966x: Fixes for when MTU is changed | expand

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Context Check Description
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers success CCed 7 of 7 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 16 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Horatiu Vultur Oct. 23, 2022, 6:48 p.m. UTC
When the MTU was changed, the lan966x didn't take in consideration
the L2 header and the FCS. So the HW was configured with a smaller
value than what was desired. Therefore the correct value to configure
the HW would be new_mtu + ETH_HLEN + ETH_FCS_LEN.
The vlan tag is not considered here, because at the time when the
blamed commit was added, there was no vlan filtering support. The
vlan fix will be part of the next patch.

Fixes: d28d6d2e37d1 ("net: lan966x: add port module support")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
---
 drivers/net/ethernet/microchip/lan966x/lan966x_main.c | 2 +-
 drivers/net/ethernet/microchip/lan966x/lan966x_main.h | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
index be2fd030cccbe..b3070c3fcad0a 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
@@ -386,7 +386,7 @@  static int lan966x_port_change_mtu(struct net_device *dev, int new_mtu)
 	int old_mtu = dev->mtu;
 	int err;
 
-	lan_wr(DEV_MAC_MAXLEN_CFG_MAX_LEN_SET(new_mtu),
+	lan_wr(DEV_MAC_MAXLEN_CFG_MAX_LEN_SET(LAN966X_HW_MTU(new_mtu)),
 	       lan966x, DEV_MAC_MAXLEN_CFG(port->chip_port));
 	dev->mtu = new_mtu;
 
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
index 9656071b8289e..4ec33999e4df6 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
@@ -26,6 +26,8 @@ 
 #define LAN966X_BUFFER_MEMORY		(160 * 1024)
 #define LAN966X_BUFFER_MIN_SZ		60
 
+#define LAN966X_HW_MTU(mtu)		((mtu) + ETH_HLEN + ETH_FCS_LEN)
+
 #define PGID_AGGR			64
 #define PGID_SRC			80
 #define PGID_ENTRIES			89