b66add7a74
With device frequency scaling, the mux clock that (indirectly) feeds the
device selects between a dedicated PLL, and some other stable clocks.
When a clk rate change is requested, the (normally) upstream PLL is
reconfigured. It's possible for the clock output of the PLL to become
unstable during this process.
To avoid causing the device to glitch, the mux should temporarily be
switched over to another "stable" clock during the PLL rate change.
This is done with clk notifiers.
This patch adds common functions for notifiers to temporarily and
transparently reparent mux clocks.
This was loosely based on commit 8adfb08605a9 ("clk: sunxi-ng: mux: Add
clk notifier functions").
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
[Angelo: Changed mtk_mux_nb to hold a pointer to clk_ops instead of mtk_mux]
Co-developed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Miles Chen <miles.chen@mediatek.com>
Link: https://lore.kernel.org/r/20220927101128.44758-4-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.