[PATCH RFC net-next 1/5] net: stmmac: call phylink_start() and phylink_stop() in XDP functions

["Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>]

Phylink does not permit drivers to mess with the netif carrier, as
this will de-synchronise phylink with the MAC driver. Moreover,
setting and clearing the TE and RE bits via stmmac_mac_set() in this
path is also wrong as the link may not be up.

Replace the netif_carrier_on(), netif_carrier_off() and
stmmac_mac_set() calls with the appropriate phylink_start() and
phylink_stop() calls, thereby allowing phylink to manage the netif
carrier and TE/RE bits through the .mac_link_up() and .mac_link_down()
methods.

Note that RE should only be set after the DMA is ready to avoid the
receive FIFO between the MAC and DMA blocks overflowing, so
phylink_start() needs to be placed after DMA has been started.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 13796b1c8d7c..84d8b1c9f6d4 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -6887,6 +6887,8 @@ void stmmac_xdp_release(struct net_device *dev)
 	/* Ensure tx function is not running */
 	netif_tx_disable(dev);
 
+	phylink_stop(priv->phylink);
+
 	/* Disable NAPI process */
 	stmmac_disable_all_queues(priv);
 
@@ -6902,14 +6904,10 @@ void stmmac_xdp_release(struct net_device *dev)
 	/* Release and free the Rx/Tx resources */
 	free_dma_desc_resources(priv, &priv->dma_conf);
 
-	/* Disable the MAC Rx/Tx */
-	stmmac_mac_set(priv, priv->ioaddr, false);
-
 	/* set trans_start so we don't get spurious
 	 * watchdogs during reset
 	 */
 	netif_trans_update(dev);
-	netif_carrier_off(dev);
 }
 
 int stmmac_xdp_open(struct net_device *dev)
@@ -6992,25 +6990,25 @@ int stmmac_xdp_open(struct net_device *dev)
 		tx_q->txtimer.function = stmmac_tx_timer;
 	}
 
-	/* Enable the MAC Rx/Tx */
-	stmmac_mac_set(priv, priv->ioaddr, true);
-
 	/* Start Rx & Tx DMA Channels */
 	stmmac_start_all_dma(priv);
 
+	phylink_start(priv->phylink);
+
 	ret = stmmac_request_irq(dev);
 	if (ret)
 		goto irq_error;
 
 	/* Enable NAPI process*/
 	stmmac_enable_all_queues(priv);
-	netif_carrier_on(dev);
 	netif_tx_start_all_queues(dev);
 	stmmac_enable_all_dma_irq(priv);
 
 	return 0;
 
 irq_error:
+	phylink_stop(priv->phylink);
+
 	for (chan = 0; chan < priv->plat->tx_queues_to_use; chan++)
 		hrtimer_cancel(&priv->dma_conf.tx_queue[chan].txtimer);
 
-- 
2.30.2