Patch "net: dsa: lan9303: Do not disable switch fabric port 0 at .probe" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

net: dsa: lan9303: Do not disable switch fabric port 0 at .probe

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:

     net-dsa-lan9303-do-not-disable-switch-fabric-port-0-at-.probe.patch

and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Egil Hjelmeland <[email protected]>
Date: Tue, 24 Oct 2017 17:14:10 +0200
Subject: net: dsa: lan9303: Do not disable switch fabric port 0 at .probe

From: Egil Hjelmeland <[email protected]>

[ Upstream commit 3c91b0c1de8d013490bbc41ce9ee8810ea5baddd ]

Make the LAN9303 work when lan9303_probe() is called twice.

For some unknown reason the LAN9303 switch fail to forward data when switch fabric port 0 TX is disabled during probe. (Write of LAN9303_MAC_TX_CFG_0 in lan9303_disable_processing_port().)

In that situation the switch fabric seem to receive frames, because the ALR is learning addresses. But no frames are transmitted on any of the ports.

In our system lan9303_probe() is called twice, first time dsa_register_switch() return -EPROBE_DEFER. As an experiment, modified the code to skip writing LAN9303_MAC_TX_CFG_0, port 0 during the first probe. Then the switch works as expected.

Resolve the problem by not calling lan9303_disable_processing_port() on port 0 during probe. Ports 1 and 2 are still disabled.

Although unsatisfying that the exact failure mechanism is not known, the patch should not cause any harm.

---
 drivers/net/dsa/lan9303-core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -569,7 +569,7 @@ static int lan9303_disable_processing(st
 {
 	int p;
 
-	for (p = 0; p < LAN9303_NUM_PORTS; p++) {
+	for (p = 1; p < LAN9303_NUM_PORTS; p++) {
 		int ret = lan9303_disable_processing_port(chip, p);
 
 		if (ret)

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/net-dsa-lan9303-do-not-disable-switch-fabric-port-0-at-.probe.patch