[PATCH] net/ethernet/freescale: rework quiesce/activate for ucc_geth

Valentin Longchamp valentin at longchamp.me
Thu May 21 01:53:50 AEST 2020

ugeth_quiesce/activate are used to halt the controller when there is a
link change that requires to reconfigure the mac.

The previous implementation called netif_device_detach(). This however
causes the initial activation of the netdevice to fail precisely because
it's detached. For details, see [1].

A possible workaround was the revert of commit
net: linkwatch: add check for netdevice being present to linkwatch_do_dev
However, the check introduced in the above commit is correct and shall be

The netif_device_detach() is thus replaced with
netif_tx_stop_all_queues() that prevents any tranmission. This allows to
perform mac config change required by the link change, without detaching
the corresponding netdevice and thus not preventing its initial

[1] https://lists.openwall.net/netdev/2020/01/08/201

Signed-off-by: Valentin Longchamp <valentin at longchamp.me>
Acked-by: Matteo Ghidoni <matteo.ghidoni at ch.abb.com>
 drivers/net/ethernet/freescale/ucc_geth.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/freescale/ucc_geth.c b/drivers/net/ethernet/freescale/ucc_geth.c
index 6e5f6dd169b5..552e7554a9f8 100644
--- a/drivers/net/ethernet/freescale/ucc_geth.c
+++ b/drivers/net/ethernet/freescale/ucc_geth.c
@@ -42,6 +42,7 @@
 #include <soc/fsl/qe/ucc.h>
 #include <soc/fsl/qe/ucc_fast.h>
 #include <asm/machdep.h>
+#include <net/sch_generic.h>
 #include "ucc_geth.h"
@@ -1548,11 +1549,8 @@ static int ugeth_disable(struct ucc_geth_private *ugeth, enum comm_dir mode)
 static void ugeth_quiesce(struct ucc_geth_private *ugeth)
-	/* Prevent any further xmits, plus detach the device. */
-	netif_device_detach(ugeth->ndev);
-	/* Wait for any current xmits to finish. */
-	netif_tx_disable(ugeth->ndev);
+	/* Prevent any further xmits */
+	netif_tx_stop_all_queues(ugeth->ndev);
 	/* Disable the interrupt to avoid NAPI rescheduling. */
@@ -1565,7 +1563,10 @@ static void ugeth_activate(struct ucc_geth_private *ugeth)
-	netif_device_attach(ugeth->ndev);
+	/* allow to xmit again  */
+	netif_tx_wake_all_queues(ugeth->ndev);
+	__netdev_watchdog_up(ugeth->ndev);
 /* Called every time the controller might need to be made

More information about the Linuxppc-dev mailing list