[PATCH 4.19 30/42] net: dsa: mv88e6xxx: Fix clearing of stats counters

Greg Kroah-Hartman
2018-11-21T19:07:33Z

From: Andrew Lunn <andrew@lunn.ch>

[ Upstream commit a9049ff9214da68df1179a7d5e36b43479abc9b8 ]

The mv88e6161 would sometime fail to probe with a timeout waiting for
the switch to complete an operation. This operation is supposed to
clear the statistics counters. However, due to a read/modify/write,
without the needed mask, the operation actually carried out was more
random, with invalid parameters, resulting in the switch not
responding. We need to preserve the histogram mode bits, so apply a
mask to keep them.

Reported-by: Chris Healy <Chris.Healy@zii.aero>
Fixes: 40cff8fca9e3 ("net: dsa: mv88e6xxx: Fix stats histogram mode")
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/dsa/mv88e6xxx/global1.c | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/net/dsa/mv88e6xxx/global1.c
+++ b/drivers/net/dsa/mv88e6xxx/global1.c
@@ -567,6 +567,8 @@ int mv88e6xxx_g1_stats_clear(struct mv88
if (err)
return err;

+ /* Keep the histogram mode bits */
+ val &= MV88E6XXX_G1_STATS_OP_HIST_RX_TX;
val |= MV88E6XXX_G1_STATS_OP_BUSY | MV88E6XXX_G1_STATS_OP_FLUSH_ALL;

err = mv88e6xxx_g1_write(chip, MV88E6XXX_G1_STATS_OP, val);