e847c7675e
If the number of lanes was forced and then subsequently the user
omits this parameter, the ksettings->lanes is reset. The driver
should then reset the number of lanes to the device's default
for the specified speed.
However, although the ksettings->lanes is set to 0, the mod variable
is not set to true to indicate the driver and userspace should be
notified of the changes.
The consequence is that the same ethtool operation will produce
different results based on the initial state.
If the initial state is:
$ ethtool swp1 | grep -A 3 'Speed: '
Speed: 500000Mb/s
Lanes: 2
Duplex: Full
Auto-negotiation: on
then executing 'ethtool -s swp1 speed 50000 autoneg off' will yield:
$ ethtool swp1 | grep -A 3 'Speed: '
Speed: 500000Mb/s
Lanes: 2
Duplex: Full
Auto-negotiation: off
While if the initial state is:
$ ethtool swp1 | grep -A 3 'Speed: '
Speed: 500000Mb/s
Lanes: 1
Duplex: Full
Auto-negotiation: off
executing the same 'ethtool -s swp1 speed 50000 autoneg off' results in:
$ ethtool swp1 | grep -A 3 'Speed: '
Speed: 500000Mb/s
Lanes: 1
Duplex: Full
Auto-negotiation: off
This patch fixes this behavior. Omitting lanes will always results in
the driver choosing the default lane width for the chosen speed. In this
scenario, regardless of the initial state, the end state will be, e.g.,
$ ethtool swp1 | grep -A 3 'Speed: '
Speed: 500000Mb/s
Lanes: 2
Duplex: Full
Auto-negotiation: off
Fixes: 012ce4dd3102 ("ethtool: Extend link modes settings uAPI with lanes")
Signed-off-by: Andy Roulin <aroulin@nvidia.com>
Reviewed-by: Danielle Ratson <danieller@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/ac238d6b-8726-8156-3810-6471291dbc7f@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@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.