04fa26bab0
It is sometimes necessary to instantiate a bit-banging MDIO bus as a platform device, without the aid of device tree. When device tree is being used, the bus is not scanned for devices, only those devices which are in device tree are probed. Without device tree, by default, all addresses on the bus are scanned. This may then find a device which is not a PHY, e.g. a switch. And the switch may have registers containing values which look like a PHY. So during the scan, a PHY device is wrongly created. After the bus has been registered, a search is made for mdio_board_info structures which indicates devices on the bus, and the driver which should be used for them. This is typically used to instantiate Ethernet switches from platform drivers. However, if the scanning of the bus has created a PHY device at the same location as indicated into the board info for a switch, the switch device is not created, since the address is already busy. This can be avoided by setting the phy_mask of the mdio bus. This mask prevents addresses on the bus being scanned. v2 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.