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Before this change, every mtk_fixed_factor clock forced clock flags to CLK_SET_RATE_PARENT: while this is harmless in some cases, it may not be desired in some others, especially when performing clock muxing on a clock having multiple parents of which one is a dedicated PLL and the others are not. This is especially seen on the GPU clocks on some SoCs, where we are muxing between multiple parents: a fixed clock (crystal), a programmable GPU PLL and one or more dividers for the MAINPLL, used for a number of devices; it happens that when a rate change is called for the GPU, the clock framework will try to satisfy the rate request by using one of the MAINPLL dividers, which have CLK_SET_RATE_PARENT and will set the rate on MAINPLL itself - overclocking or underclocking many devices in the system - and making it to lock up. Logically, it should be harmless (and would only reduce possible bugs) to change all of the univpll and mainpll related fixed factor clocks to not declare the CLK_SET_RATE_PARENT by default but, on some SoCs, this is also used for dividers of other PLLs for which a rate change based on the divider may be desired, hence introduce a new FACTOR_FLAGS() macro to use custom flags (or none) on selected fixed factor clocks. Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Reviewed-by: Chen-Yu Tsai <wenst@chromium.org> Link: https://lore.kernel.org/r/20221024102307.33722-2-angelogioacchino.delregno@collabora.com Signed-off-by: Chen-Yu Tsai <wenst@chromium.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.