3d4937c6a3
[ Upstream commit dbae3388ea9ca33bd1d5eabc3b0ef17e69c74677 ]
On mv88e6xxx 1G/2.5G PCS, the SerDes register 4.2001.2 has the following
description:
This register bit indicates when link was lost since the last
read. For the current link status, read this register
back-to-back.
Thus to get current link state, we need to read the register twice.
But doing that in the link change interrupt handler would lead to
potentially ignoring link down events, which we really want to avoid.
Thus this needs to be solved in phylink's resolve, by retriggering
another resolve in the event when PCS reports link down and previous
link was up, and by re-reading PCS state if the previous link was down.
The wrong value is read when phylink requests change from sgmii to
2500base-x mode, and link won't come up. This fixes the bug.
Fixes: 9525ae83959b ("phylink: add phylink infrastructure")
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.