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The BD9571MWV PMIC supports backup mode, which keeps one or more DDR
rails powered while the main SoC is powered down.
Which DDR rails are to be kept powered is board-specific, and controlled
using the optional "rohm,ddr-backup-power" DT property. In the absence
of this property, backup mode is not available.
Backup mode can be enabled or disabled by the user using the standard
"wakeup" virtual file in sysfs, e.g. to enable:
echo enabled > /sys/devices/platform/soc/e60b0000.i2c/i2c-7/7-0030/bd9571mwv-regulator.2.auto/power/wakeup
When the PMIC is configured for backup mode, the role of the accessory
power switch changes from a power switch to a wake-up switch.
Two types of switches (or signals) can be used:
A. With a momentary power switch (or pulse signal), the PMIC is
configured for backup mode in the PMIC driver's suspend callback,
during system suspend.
Backup mode is enabled by default, as there is no further impact
during normal system operation.
B. With a toggle power switch (or level signal), the following steps
must be followed exactly:
1. Configure PMIC for backup mode,
2. Switch accessory power switch off, to prepare for system
suspend, which is a manual step not controlled by software,
3. Suspend system.
This mode is not yet supported by the driver.
As the switch type is board-specific, and cannot be determined
automatically, it is obtained from the presence of one of the
"rohm,rstbmode-*" properties in DT.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
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| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
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| .mailmap | ||
| COPYING | ||
| CREDITS | ||
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| README | ||
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.