From: Roland Hii <roland.king.guan.hii@intel.com>
Date: Wed, 19 Jun 2019 22:41:48 +0800
Subject: net: stmmac: set IC bit when transmitting frames with HW timestamp
Git-commit: d0bb82fd60183868f46c8ccc595a3d61c3334a18
Patch-mainline: 5.2-rc7
References: networking-stable-19_07_02

When transmitting certain PTP frames, e.g. SYNC and DELAY_REQ, the
PTP daemon, e.g. ptp4l, is polling the driver for the frame transmit
hardware timestamp. The polling will most likely timeout if the tx
coalesce is enabled due to the Interrupt-on-Completion (IC) bit is
not set in tx descriptor for those frames.

This patch will ignore the tx coalesce parameter and set the IC bit
when transmitting PTP frames which need to report out the frame
transmit hardware timestamp to user space.

[js] the if is not switched in 4.12 yet, so just add the conditions

Fixes: f748be531d70 ("net: stmmac: Rework coalesce timer and fix multi-queue races")
Signed-off-by: Roland Hii <roland.king.guan.hii@intel.com>
Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: Voon Weifeng <weifeng.voon@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2937,7 +2937,10 @@ static netdev_tx_t stmmac_tso_xmit(struc
 
 	/* Manage tx mitigation */
 	priv->tx_count_frames += nfrags + 1;
-	if (likely(priv->tx_coal_frames > priv->tx_count_frames)) {
+	if (likely(priv->tx_coal_frames > priv->tx_count_frames) &&
+	    !(priv->synopsys_id >= DWMAC_CORE_4_00 &&
+	    (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) &&
+	    priv->hwts_tx_en)) {
 		mod_timer(&priv->txtimer,
 			  STMMAC_COAL_TIMER(priv->tx_coal_timer));
 	} else {
@@ -3148,7 +3151,10 @@ static netdev_tx_t stmmac_xmit(struct sk
 	 * element in case of no SG.
 	 */
 	priv->tx_count_frames += nfrags + 1;
-	if (likely(priv->tx_coal_frames > priv->tx_count_frames)) {
+	if (likely(priv->tx_coal_frames > priv->tx_count_frames) &&
+	    !(priv->synopsys_id >= DWMAC_CORE_4_00 &&
+	    (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) &&
+	    priv->hwts_tx_en)) {
 		mod_timer(&priv->txtimer,
 			  STMMAC_COAL_TIMER(priv->tx_coal_timer));
 	} else {