net: stmmac: perserve TX and RX coalesce value during XDP setup

commit 61da6ac upstream.

When XDP program is loaded, it is desirable that the previous TX and RX
coalesce values are not re-inited to its default value. This prevents
unnecessary re-configurig the coalesce values that were working fine
before.

Fixes: ac746c8 ("net: stmmac: enhance XDP ZC driver level switching performance")
Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Tested-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/20211124114019.3949125-1-boon.leong.ong@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -6596,6 +6596,9 @@ int stmmac_xdp_open(struct net_device *dev)
 		tx_q->tx_tail_addr = tx_q->dma_tx_phy;
 		stmmac_set_tx_tail_ptr(priv, priv->ioaddr,
 				       tx_q->tx_tail_addr, chan);
+
+		hrtimer_init(&tx_q->txtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+		tx_q->txtimer.function = stmmac_tx_timer;
 	}
 
 	/* Enable the MAC Rx/Tx */
@@ -6604,8 +6607,6 @@ int stmmac_xdp_open(struct net_device *dev)
 	/* Start Rx & Tx DMA Channels */
 	stmmac_start_all_dma(priv);
 
-	stmmac_init_coalesce(priv);
-
 	ret = stmmac_request_irq(dev);
 	if (ret)
 		goto irq_error;