09bbedac72
Some multigig SFPs from RollBall and Hilink do not expose functional MDIO access to the internal PHY of the SFP via I2C address 0x56 (although there seems to be read-only clause 22 access on this address). Instead these SFPs PHY can be accessed via I2C via the SFP Enhanced Digital Diagnostic Interface - I2C address 0x51. The SFP_PAGE has to be selected to 3 and the password must be filled with 0xff bytes for this PHY communication to work. This extends the mdio-i2c driver to support this protocol by adding a special parameter to mdio_i2c_alloc function via which this RollBall protocol can be selected. Signed-off-by: Marek Behún <kabel@kernel.org> Cc: Andrew Lunn <andrew@lunn.ch> Cc: 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.