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PLLE has a hardware power sequencer logic which is a state machine that can power on/off PLLE without any software intervention. The sequencer has two inputs, one from XUSB UPHY PLL and the other from SATA UPHY PLL. PLLE provides reference clock to XUSB and SATA UPHY PLLs. When both of the downstream PLLs are powered-off, PLLE hardware power sequencer will automatically power off PLLE for power saving. XUSB and SATA UPHY PLLs also have their own hardware power sequencer logic. XUSB UPHY PLL is shared between XUSB SuperSpeed ports and PCIE controllers. The XUSB UPHY PLL hardware power sequencer has inputs from XUSB and PCIE. When all of the XUSB SuperSpeed ports and PCIE controllers are in low power state, XUSB UPHY PLL hardware power sequencer automatically power off PLL and flags idle to PLLE hardware power sequencer. Similar applies to SATA UPHY PLL. PLLE hardware power sequencer has to be enabled after both downstream sequencers are enabled. This commit adds two helper functions: 1. tegra210_plle_hw_sequence_start() for XUSB PADCTL driver to enable PLLE hardware sequencer at proper time. 2. tegra210_plle_hw_sequence_is_enabled() for XUSB PADCTL driver to check whether PLLE hardware sequencer has been enabled or not. Signed-off-by: JC Kuo <jckuo@nvidia.com> Acked-by: Thierry Reding <treding@nvidia.com> Acked-by: Stephen Boyd <sboyd@kernel.org> Signed-off-by: Thierry Reding <treding@nvidia.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.