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Russell King
d14e078f23
mac_config() can be called at any point, and the expected behaviour from MAC drivers is to only reprogram when necessary - and certainly avoid taking the link down on every call. Unfortunately, mvpp2 does exactly that - it takes the link down, and reprograms everything, and then releases the forced-link down. This is bad, it can cause the link to bounce: - SFP detects signal, disables LOS indication. - SFP code calls into phylink, calling phylink_sfp_link_up() which triggers a resolve. - phylink_resolve() calls phylink_get_mac_state() and finds the MAC reporting link up. - phylink wants to configure the pause mode on the MAC, so calls phylink_mac_config() - mvpp2 takes the link down temporarily, generating a MAC link down event followed by another MAC link event. - phylink calls mac_link_up() and then processes the MAC link down event. - phylink_resolve() gets called again, registers the link down, and calls mach_link_down() before re-running itself. - phylink_resolve() starts again at step 3 above. This sequence repeats. GMAC versions prior to mvpp2 do not require the link to be taken down except when certain link properties (eg, switching between SGMII and 1000base-X mode, or enabling/disabling in-band negotiation) are changed. Implement this for mvpp2. 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>
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.