netdev - [PATCH net-next 1/5] sky2: force receive checksum when using RSS on some hardware (v2)

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Date:	Thu, 7 Jul 2011 16:40:00 -0700
From:	Stephen Hemminger <shemminger@...tta.com>
To:	Stephen Hemminger <shemminger@...tta.com>
Cc:	Michał Mirosław <mirqus@...il.com>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: [PATCH net-next 1/5] sky2: force receive checksum when using RSS on
 some hardware (v2)

Found when reviewing the vendor driver. Apparently some chip versions
require receive checksumming to be enabled in order for RSS to work.

Also, if fix_features has to change some settings; put in message
in log in similar manner to netdev_fix_features.

Signed-off-by: Stephen Hemminger <shemminger@...tta.com>

---
v2 - enforce the requirement in fix_features rather than set features

--- a/drivers/net/sky2.c	2011-07-07 13:56:03.575420273 -0700
+++ b/drivers/net/sky2.c	2011-07-07 14:03:17.775403938 -0700
@@ -2996,7 +2996,8 @@ static int __devinit sky2_init(struct sk
 		hw->flags = SKY2_HW_GIGABIT
 			| SKY2_HW_NEWER_PHY
 			| SKY2_HW_NEW_LE
-			| SKY2_HW_ADV_POWER_CTL;
+			| SKY2_HW_ADV_POWER_CTL
+			| SKY2_HW_RSS_CHKSUM;
 
 		/* New transmit checksum */
 		if (hw->chip_rev != CHIP_REV_YU_EX_B0)
@@ -3024,7 +3025,7 @@ static int __devinit sky2_init(struct sk
 
 		/* The workaround for status conflicts VLAN tag detection. */
 		if (hw->chip_rev == CHIP_REV_YU_FE2_A0)
-			hw->flags |= SKY2_HW_VLAN_BROKEN;
+			hw->flags |= SKY2_HW_VLAN_BROKEN | SKY2_HW_RSS_CHKSUM;
 		break;
 
 	case CHIP_ID_YUKON_SUPR:
@@ -3033,6 +3034,9 @@ static int __devinit sky2_init(struct sk
 			| SKY2_HW_NEW_LE
 			| SKY2_HW_AUTO_TX_SUM
 			| SKY2_HW_ADV_POWER_CTL;
+
+		if (hw->chip_rev == CHIP_REV_YU_SU_A0)
+			hw->flags |= SKY2_HW_RSS_CHKSUM;
 		break;
 
 	case CHIP_ID_YUKON_UL_2:
@@ -4176,8 +4180,18 @@ static u32 sky2_fix_features(struct net_
 	/* In order to do Jumbo packets on these chips, need to turn off the
 	 * transmit store/forward. Therefore checksum offload won't work.
 	 */
-	if (dev->mtu > ETH_DATA_LEN && hw->chip_id == CHIP_ID_YUKON_EC_U)
+	if (dev->mtu > ETH_DATA_LEN && hw->chip_id == CHIP_ID_YUKON_EC_U) {
+		netdev_warn(dev, "checksum offload not possible with jumbo frames\n");
 		features &= ~(NETIF_F_TSO|NETIF_F_SG|NETIF_F_ALL_CSUM);
+	}
+
+	/* Some hardware requires receive checksum for RSS to work. */
+	if ( (features & NETIF_F_RXHASH) &&
+	     !(features & NETIF_F_RXCSUM) &&
+	     (sky2->hw->flags & SKY2_HW_RSS_CHKSUM)) {
+		netdev_warn(dev, "receive hashing forces receive checksum\n");
+		features |= NETIF_F_RXCSUM;
+	}
 
 	return features;
 }
--- a/drivers/net/sky2.h	2011-07-07 13:56:03.563420272 -0700
+++ b/drivers/net/sky2.h	2011-07-07 13:56:07.719420117 -0700
@@ -2281,6 +2281,7 @@ struct sky2_hw {
 #define SKY2_HW_ADV_POWER_CTL	0x00000080	/* additional PHY power regs */
 #define SKY2_HW_RSS_BROKEN	0x00000100
 #define SKY2_HW_VLAN_BROKEN     0x00000200
+#define SKY2_HW_RSS_CHKSUM	0x00000400	/* RSS requires chksum */
 
 	u8	     	     chip_id;
 	u8		     chip_rev;

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