linux-kernel - [PATCH 4.12 38/52] gianfar: Fix Tx flow control deactivation

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Date:   Mon, 18 Sep 2017 11:11:32 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Claudiu Manoil <claudiu.manoil@....com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.12 38/52] gianfar: Fix Tx flow control deactivation

4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Claudiu Manoil <claudiu.manoil@....com>

[ Upstream commit 5d621672bc1a1e5090c1ac5432a18c79e0e13e03 ]

The wrong register is checked for the Tx flow control bit,
it should have been maccfg1 not maccfg2.
This went unnoticed for so long probably because the impact is
hardly visible, not to mention the tangled code from adjust_link().
First, link flow control (i.e. handling of Rx/Tx link level pause frames)
is disabled by default (needs to be enabled via 'ethtool -A').
Secondly, maccfg2 always returns 0 for tx_flow_oldval (except for a few
old boards), which results in Tx flow control remaining always on
once activated.

Fixes: 45b679c9a3ccd9e34f28e6ec677b812a860eb8eb ("gianfar: Implement PAUSE frame generation support")
Signed-off-by: Claudiu Manoil <claudiu.manoil@....com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/ethernet/freescale/gianfar.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -3687,7 +3687,7 @@ static noinline void gfar_update_link_st
 		u32 tempval1 = gfar_read(&regs->maccfg1);
 		u32 tempval = gfar_read(&regs->maccfg2);
 		u32 ecntrl = gfar_read(&regs->ecntrl);
-		u32 tx_flow_oldval = (tempval & MACCFG1_TX_FLOW);
+		u32 tx_flow_oldval = (tempval1 & MACCFG1_TX_FLOW);

 		if (phydev->duplex != priv->oldduplex) {
 			if (!(phydev->duplex))