tg3: Add workaround to restrict 5762 MRRS to 2048

[ Upstream commit 4419bb1c ]

One of AMD based server with 5762 hangs with jumbo frame traffic.
This AMD platform has southbridge limitation which is restricting MRRS
to 4000. As a work around, driver to restricts the MRRS to 2048 for
this particular 5762 NX1 card.
Signed-off-by: Siva Reddy Kallam <siva.kallam@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/broadcom/tg3.c

@@ -10051,6 +10051,16 @@ static int tg3_reset_hw(struct tg3 *tp, bool reset_phy)
 
 	tw32(GRC_MODE, tp->grc_mode | val);
 
+	/* On one of the AMD platform, MRRS is restricted to 4000 because of
+	 * south bridge limitation. As a workaround, Driver is setting MRRS
+	 * to 2048 instead of default 4096.
+	 */
+	if (tp->pdev->subsystem_vendor == PCI_VENDOR_ID_DELL &&
+	    tp->pdev->subsystem_device == TG3PCI_SUBDEVICE_ID_DELL_5762) {
+		val = tr32(TG3PCI_DEV_STATUS_CTRL) & ~MAX_READ_REQ_MASK;
+		tw32(TG3PCI_DEV_STATUS_CTRL, val | MAX_READ_REQ_SIZE_2048);
+	}
+
 	/* Setup the timer prescalar register.  Clock is always 66Mhz. */
 	val = tr32(GRC_MISC_CFG);
 	val &= ~0xff;

drivers/net/ethernet/broadcom/tg3.h

@@ -95,6 +95,7 @@
 #define TG3PCI_SUBDEVICE_ID_DELL_JAGUAR		0x0106
 #define TG3PCI_SUBDEVICE_ID_DELL_MERLOT		0x0109
 #define TG3PCI_SUBDEVICE_ID_DELL_SLIM_MERLOT	0x010a
+#define TG3PCI_SUBDEVICE_ID_DELL_5762		0x07f0
 #define TG3PCI_SUBVENDOR_ID_COMPAQ		PCI_VENDOR_ID_COMPAQ
 #define TG3PCI_SUBDEVICE_ID_COMPAQ_BANSHEE	0x007c
 #define TG3PCI_SUBDEVICE_ID_COMPAQ_BANSHEE_2	0x009a
@@ -280,6 +281,9 @@
 #define TG3PCI_STD_RING_PROD_IDX	0x00000098 /* 64-bit */
 #define TG3PCI_RCV_RET_RING_CON_IDX	0x000000a0 /* 64-bit */
 /* 0xa8 --> 0xb8 unused */
+#define TG3PCI_DEV_STATUS_CTRL		0x000000b4
+#define  MAX_READ_REQ_SIZE_2048		 0x00004000
+#define  MAX_READ_REQ_MASK		 0x00007000
 #define TG3PCI_DUAL_MAC_CTRL		0x000000b8
 #define  DUAL_MAC_CTRL_CH_MASK		 0x00000003
 #define  DUAL_MAC_CTRL_ID		 0x00000004