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In some cases the hardware that the bootloader has left configured depends on RPMH power domains for their operation up until the point where the related Linux device driver probes and can inherit that configuration, or power down the hardware gracefully. Unfortunately as Linux probes the releavant drivers in sequence there are periods during the Linux boot flow where either the genpd refcount will reach 0, or worse where the active performance_state votes does not meet the requirements of the state that the hardware was left in. One specific example of this is during boot of e.g. SM8150/SC8180X, where the display clock controller probes, without any particular performance state needs (to access its registers). This will drop the MMCX rail to MIN_SVS, which isn't sufficient to sustain the clock rates that the later probing MDP is configured to. This results in an unrecoverable system state. Handle both these cases by keeping the RPMH power-domais that are referenced voted for highest state, until sync_state indicates that all devices referencing the RPMH power-domain driver has been probed. Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Reviewed-by: Caleb Connolly <caleb@connolly.tech> Reviewed-by: Konrad Dybcio <konrad.dybcio@somainline.org> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> [bjorn: Added print for sync_state errors] Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com> Signed-off-by: Bjorn Andersson <andersson@kernel.org> Link: https://lore.kernel.org/r/20220915205559.14574-1-quic_bjorande@quicinc.com
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.