5c1c42c49b
Nothing stops a clk controller from registering an OF clk provider before registering those clks with the clk framework. This is not great but we deal with it in the clk framework by refusing to hand out struct clk pointers when 'hw->core' is NULL, the indication that clk_register() has been called. Within clk_core_fill_parent_index() we considered this case when a clk_hw pointer is referenced directly by filling in the parent cache with an -EPROBE_DEFER pointer when the core pointer is NULL. When we lookup a parent with clk_core_get() we don't care about the return value being NULL though, because that was considered largely impossible, but it's been proven now that it can be NULL if two clk providers are probing in parallel and the parent provider has been registered before the clk has. Let's check for NULL here as well and treat it the same as direct clk_hw references. Signed-off-by: Stephen Boyd <sboyd@kernel.org> Link: https://lore.kernel.org/r/20211208041534.3928718-1-sboyd@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.