0853787db2
[ Upstream commit 2a97d55333e4299f32c98cca6dc5c4db1c5855fc ] The Renesas Compare Match Timer 0 and 1 (CMT0/1) variants have a register to control the clock supply to the individual channels. Currently the driver does not touch this register, and relies on the documented initial value, which has the clock supply enabled for all channels present. However, when Linux starts on the APE6-EVM development board, only the clock supply to the first CMT1 channel is enabled. Hence the first channel (used as a clockevent) works, while the second channel (used as a clocksource) does not. Note that the default system clocksource is the Cortex-A15 architectured timer, and the user needs to manually switch to the CMT1 clocksource to trigger the broken behavior. Fix this by removing the fragile dependency on implicit reset and/or boot loader state, and by enabling the clock supply explicitly for all channels used instead. This requires postponing the clk_disable() call, else the timer's registers cannot be accessed in sh_cmt_setup_channel(). Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Link: https://lore.kernel.org/r/20201210194648.2901899-1-geert+renesas@glider.be Stable-dep-of: 3f44f7156f59 ("clocksource/drivers/sh_cmt: Access registers according to spec") Signed-off-by: Sasha Levin <sashal@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.