From 7816d6e70449bc8ff12cdfb042fa7fab69ad6361 Mon Sep 17 00:00:00 2001
From: Jongsung Kim <neidhard.kim@lge.com>
Date: Fri, 6 Dec 2019 20:40:00 +0900
Subject: [PATCH] net: stmmac: reset Tx desc base address before restarting Tx
Git-commit: f421031e3ff0dd288a6e1bbde9aa41a25bb814e6
References: git-fixes
Patch-mainline: v5.5-rc1

Refer to the databook of DesignWare Cores Ethernet MAC Universal:

6.2.1.5 Register 4 (Transmit Descriptor List Address Register

If this register is not changed when the ST bit is set to 0, then
the DMA takes the descriptor address where it was stopped earlier.

The stmmac_tx_err() does zero indices to Tx descriptors, but does
not reset HW current Tx descriptor address. To fix inconsistency,
the base address of the Tx descriptors should be rewritten before
restarting Tx.

Signed-off-by: Jongsung Kim <neidhard.kim@lge.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 0af514fb3bb0..fa37e5a59de2 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1975,6 +1975,8 @@ static void stmmac_tx_err(struct stmmac_priv *priv, u32 chan)
 	tx_q->cur_tx = 0;
 	tx_q->mss = 0;
 	netdev_tx_reset_queue(netdev_get_tx_queue(priv->dev, chan));
+	stmmac_init_tx_chan(priv, priv->ioaddr, priv->plat->dma_cfg,
+			    tx_q->dma_tx_phy, chan);
 	stmmac_start_tx_dma(priv, chan);
 
 	priv->dev->stats.tx_errors++;
-- 
2.16.4