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Up until now we have managed not to have the mdio-bcm-unimac manage its clock except during probe and suspend/resume. This works most of the time, except where it does not. With a fully modular build, we can get into a situation whereby the GENET driver is fully registered, and so is the mdio-bcm-unimac driver, however the Ethernet PHY driver is not yet, because it depends on a resource that is not yet available (e.g.: GPIO provider). In that state, the network device is not usable yet, and so to conserve power, the GENET driver will have turned off its "main" clock which feeds its MDIO controller. When the PHY driver finally probes however, we make an access to the PHY registers to e.g.: disable interrupts, and this causes a bus error within the MDIO controller space because the MDIO controller clock(s) are turned off. To remedy that, we manage the clock around all of the I/O accesses to the hardware which are done exclusively during read, write and clock divider configuration. This ensures that the register space is accessible, and this also ensures that there are not unnecessarily elevated reference counts keeping the clocks active when the network device is administratively turned off. It would be the case with the previous way of managing the clock. Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.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.