From: Bryan Whitehead <Bryan.Whitehead@microchip.com>
Date: Tue, 26 Feb 2019 19:06:26 +0000 (-0500)
Subject: lan743x: Fix TX Stall Issue
X-Git-Tag: rel_imx_4.19.35_1.1.0~6143
X-Git-Url: https://git.somdevices.com/?a=commitdiff_plain;h=ceb7c249869527f28e8caf6989b616740bd454e0;p=linux.git

lan743x: Fix TX Stall Issue

[ Upstream commit 90490ef7269906423a1c1b917fc24be8b1602658 ]

It has been observed that tx queue stalls while downloading
from certain web sites (example www.speedtest.net)

The cause has been tracked down to a corner case where
dma descriptors where not setup properly. And there for a tx
completion interrupt was not signaled.

This fix corrects the problem by properly marking the end of
a multi descriptor transmission.

Fixes: 23f0703c125b ("lan743x: Add main source files for new lan743x driver")
Signed-off-by: Bryan Whitehead <Bryan.Whitehead@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c
index 42f5bfa33694..de5a6abda7e3 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -1403,7 +1403,8 @@ static int lan743x_tx_frame_start(struct lan743x_tx *tx,
 }
 
 static void lan743x_tx_frame_add_lso(struct lan743x_tx *tx,
-				     unsigned int frame_length)
+				     unsigned int frame_length,
+				     int nr_frags)
 {
 	/* called only from within lan743x_tx_xmit_frame.
 	 * assuming tx->ring_lock has already been acquired.
@@ -1413,6 +1414,10 @@ static void lan743x_tx_frame_add_lso(struct lan743x_tx *tx,
 
 	/* wrap up previous descriptor */
 	tx->frame_data0 |= TX_DESC_DATA0_EXT_;
+	if (nr_frags <= 0) {
+		tx->frame_data0 |= TX_DESC_DATA0_LS_;
+		tx->frame_data0 |= TX_DESC_DATA0_IOC_;
+	}
 	tx_descriptor = &tx->ring_cpu_ptr[tx->frame_tail];
 	tx_descriptor->data0 = tx->frame_data0;
 
@@ -1517,8 +1522,11 @@ static void lan743x_tx_frame_end(struct lan743x_tx *tx,
 	u32 tx_tail_flags = 0;
 
 	/* wrap up previous descriptor */
-	tx->frame_data0 |= TX_DESC_DATA0_LS_;
-	tx->frame_data0 |= TX_DESC_DATA0_IOC_;
+	if ((tx->frame_data0 & TX_DESC_DATA0_DTYPE_MASK_) ==
+	    TX_DESC_DATA0_DTYPE_DATA_) {
+		tx->frame_data0 |= TX_DESC_DATA0_LS_;
+		tx->frame_data0 |= TX_DESC_DATA0_IOC_;
+	}
 
 	tx_descriptor = &tx->ring_cpu_ptr[tx->frame_tail];
 	buffer_info = &tx->buffer_info[tx->frame_tail];
@@ -1603,7 +1611,7 @@ static netdev_tx_t lan743x_tx_xmit_frame(struct lan743x_tx *tx,
 	}
 
 	if (gso)
-		lan743x_tx_frame_add_lso(tx, frame_length);
+		lan743x_tx_frame_add_lso(tx, frame_length, nr_frags);
 
 	if (nr_frags <= 0)
 		goto finish;