netdev - [PATCH net-next v2 3/5] net: macb: add no LSO capability (MACB_CAPS_NO

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Message-Id: <20251022-macb-eyeq5-v2-3-7c140abb0581@bootlin.com>
Date: Wed, 22 Oct 2025 09:38:12 +0200
From: Théo Lebrun <theo.lebrun@...tlin.com>
To: Andrew Lunn <andrew+netdev@...n.ch>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Nicolas Ferre <nicolas.ferre@...rochip.com>, 
 Claudiu Beznea <claudiu.beznea@...on.dev>, 
 Russell King <linux@...linux.org.uk>
Cc: netdev@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 Benoît Monin <benoit.monin@...tlin.com>, 
 Grégory Clement <gregory.clement@...tlin.com>, 
 Maxime Chevallier <maxime.chevallier@...tlin.com>, 
 Tawfik Bayouk <tawfik.bayouk@...ileye.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>, 
 Théo Lebrun <theo.lebrun@...tlin.com>, 
 Andrew Lunn <andrew@...n.ch>
Subject: [PATCH net-next v2 3/5] net: macb: add no LSO capability
 (MACB_CAPS_NO_LSO)

LSO is runtime-detected using the PBUF_LSO field inside register DCFG6.
Allow disabling that feature if it is broken by using bp->caps coming
from match data.

Reviewed-by: Andrew Lunn <andrew@...n.ch>
Signed-off-by: Théo Lebrun <theo.lebrun@...tlin.com>
---
 drivers/net/ethernet/cadence/macb.h      | 1 +
 drivers/net/ethernet/cadence/macb_main.c | 7 +++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 93e8dd092313..05bfa9bd4782 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -778,6 +778,7 @@
 #define MACB_CAPS_DMA_64B			BIT(21)
 #define MACB_CAPS_DMA_PTP			BIT(22)
 #define MACB_CAPS_RSC				BIT(23)
+#define MACB_CAPS_NO_LSO			BIT(24)

 /* LSO settings */
 #define MACB_LSO_UFO_ENABLE			0x01
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 0817a99bb369..71a472c85a23 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -4562,8 +4562,11 @@ static int macb_init(struct platform_device *pdev)
 	/* Set features */
 	dev->hw_features = NETIF_F_SG;

-	/* Check LSO capability */
-	if (GEM_BFEXT(PBUF_LSO, gem_readl(bp, DCFG6)))
+	/* Check LSO capability; runtime detection can be overridden by a cap
+	 * flag if the hardware is known to be buggy
+	 */
+	if (!(bp->caps & MACB_CAPS_NO_LSO) &&
+	    GEM_BFEXT(PBUF_LSO, gem_readl(bp, DCFG6)))
 		dev->hw_features |= MACB_NETIF_LSO;

 	/* Checksum offload is only available on gem with packet buffer */

-- 
2.51.1