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net: marvell: mvpp2: fix stuck in-band SGMII negotiation
authorRussell King <rmk+kernel@armlinux.org.uk>
Fri, 8 Feb 2019 15:35:43 +0000 (15:35 +0000)
committerDavid S. Miller <davem@davemloft.net>
Sat, 9 Feb 2019 07:08:39 +0000 (23:08 -0800)
commit316734fdcf70900a83065360cff11a5826919067
treed47441fba13d1b8ab31076776d8b5bcc9764cd8e
parent388ca27ffd21c6b31d6378d4b24b7c49066848a0
net: marvell: mvpp2: fix stuck in-band SGMII negotiation

It appears that the mvpp22 can get stuck with SGMII negotiation.  The
symptoms are that in-band negotiation never completes and the partner
(eg, PHY) never reports SGMII link up, or if it supports negotiation
bypass, goes into negotiation bypass mode (which will happen when the
PHY sees that the MAC is alive but gets no response.)

Triggering the PHY end of the link to re-negotiate results in the
bypass bit clearing on the PHY, and then re-setting - indicating that
the problem is at the mvpp22 GMAC end.

Asserting the GMAC reset and de-asserting it resolves the issue.
Arrange to assert the GMAC reset at probe time, and deassert it only
after we have configured the GMAC for the appropriate mode.  This
resolves the issue.

Tested-by: Sven Auhagen <sven.auhagen@voleatech.de>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c