diff mbox series

[net,v4,3/3] net: ethernet: cortina: Fix MTU max setting

Message ID 20231109-gemini-largeframe-fix-v4-3-6e611528db08@linaro.org (mailing list archive)
State Accepted
Commit dc6c0bfbaa947dd7976e30e8c29b10c868b6fa42
Delegated to: Netdev Maintainers
Headers show
Series Fix large frames in the Gemini ethernet driver | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1273 this patch: 1273
netdev/cc_maintainers success CCed 8 of 8 maintainers
netdev/build_clang success Errors and warnings before: 1301 this patch: 1301
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
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: 1301 this patch: 1301
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 45 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Linus Walleij Nov. 9, 2023, 9:03 a.m. UTC 
The RX max frame size is over 10000 for the Gemini ethernet,
but the TX max frame size is actually just 2047 (0x7ff after
checking the datasheet). Reflect this in what we offer to Linux,
cap the MTU at the TX max frame minus ethernet headers.

We delete the code disabling the hardware checksum for large
MTUs as netdev->mtu can no longer be larger than
netdev->max_mtu meaning the if()-clause in gmac_fix_features()
is never true.

Fixes: 4d5ae32f5e1e ("net: ethernet: Add a driver for Gemini gigabit ethernet")
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/net/ethernet/cortina/gemini.c | 17 ++++-------------
 drivers/net/ethernet/cortina/gemini.h |  2 +-
 2 files changed, 5 insertions(+), 14 deletions(-)

Comments

Vladimir Oltean Nov. 9, 2023, 10:47 a.m. UTC | #1 
On Thu, Nov 09, 2023 at 10:03:14AM +0100, Linus Walleij wrote:
> The RX max frame size is over 10000 for the Gemini ethernet,
> but the TX max frame size is actually just 2047 (0x7ff after
> checking the datasheet). Reflect this in what we offer to Linux,
> cap the MTU at the TX max frame minus ethernet headers.
> 
> We delete the code disabling the hardware checksum for large
> MTUs as netdev->mtu can no longer be larger than
> netdev->max_mtu meaning the if()-clause in gmac_fix_features()
> is never true.
> 
> Fixes: 4d5ae32f5e1e ("net: ethernet: Add a driver for Gemini gigabit ethernet")
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---

Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
diff mbox series

Patch

diff --git a/drivers/net/ethernet/cortina/gemini.c b/drivers/net/ethernet/cortina/gemini.c
index dbbccef86516..636949737d72 100644
--- a/drivers/net/ethernet/cortina/gemini.c
+++ b/drivers/net/ethernet/cortina/gemini.c
@@ -2000,15 +2000,6 @@  static int gmac_change_mtu(struct net_device *netdev, int new_mtu)
 	return 0;
 }
 
-static netdev_features_t gmac_fix_features(struct net_device *netdev,
-					   netdev_features_t features)
-{
-	if (netdev->mtu + ETH_HLEN + VLAN_HLEN > MTU_SIZE_BIT_MASK)
-		features &= ~GMAC_OFFLOAD_FEATURES;
-
-	return features;
-}
-
 static int gmac_set_features(struct net_device *netdev,
 			     netdev_features_t features)
 {
@@ -2234,7 +2225,6 @@  static const struct net_device_ops gmac_351x_ops = {
 	.ndo_set_mac_address	= gmac_set_mac_address,
 	.ndo_get_stats64	= gmac_get_stats64,
 	.ndo_change_mtu		= gmac_change_mtu,
-	.ndo_fix_features	= gmac_fix_features,
 	.ndo_set_features	= gmac_set_features,
 };
 
@@ -2486,11 +2476,12 @@  static int gemini_ethernet_port_probe(struct platform_device *pdev)
 
 	netdev->hw_features = GMAC_OFFLOAD_FEATURES;
 	netdev->features |= GMAC_OFFLOAD_FEATURES | NETIF_F_GRO;
-	/* We can handle jumbo frames up to 10236 bytes so, let's accept
-	 * payloads of 10236 bytes minus VLAN and ethernet header
+	/* We can receive jumbo frames up to 10236 bytes but only
+	 * transmit 2047 bytes so, let's accept payloads of 2047
+	 * bytes minus VLAN and ethernet header
 	 */
 	netdev->min_mtu = ETH_MIN_MTU;
-	netdev->max_mtu = 10236 - VLAN_ETH_HLEN;
+	netdev->max_mtu = MTU_SIZE_BIT_MASK - VLAN_ETH_HLEN;
 
 	port->freeq_refill = 0;
 	netif_napi_add(netdev, &port->napi, gmac_napi_poll);
diff --git a/drivers/net/ethernet/cortina/gemini.h b/drivers/net/ethernet/cortina/gemini.h
index 99efb1155743..24bb989981f2 100644
--- a/drivers/net/ethernet/cortina/gemini.h
+++ b/drivers/net/ethernet/cortina/gemini.h
@@ -502,7 +502,7 @@  union gmac_txdesc_3 {
 #define SOF_BIT			0x80000000
 #define EOF_BIT			0x40000000
 #define EOFIE_BIT		BIT(29)
-#define MTU_SIZE_BIT_MASK	0x1fff
+#define MTU_SIZE_BIT_MASK	0x7ff /* Max MTU 2047 bytes */
 
 /* GMAC Tx Descriptor */
 struct gmac_txdesc {