295ab96f47
Certain drivers may need to send management traffic to the switch for things like register access, FDB dump, etc, to accelerate what their slow bus (SPI, I2C, MDIO) can already do. Ethernet is faster (especially in bulk transactions) but is also more unreliable, since the user may decide to bring the DSA master down (or not bring it up), therefore severing the link between the host and the attached switch. Drivers needing Ethernet-based register access already should have fallback logic to the slow bus if the Ethernet method fails, but that fallback may be based on a timeout, and the I/O to the switch may slow down to a halt if the master is down, because every Ethernet packet will have to time out. The driver also doesn't have the option to turn off Ethernet-based I/O momentarily, because it wouldn't know when to turn it back on. Which is where this change comes in. By tracking NETDEV_CHANGE, NETDEV_UP and NETDEV_GOING_DOWN events on the DSA master, we should know the exact interval of time during which this interface is reliably available for traffic. Provide this information to switches so they can use it as they wish. An helper is added dsa_port_master_is_operational() to check if a master port is operational. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> 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.