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Enable the rtc node on VIM1/VIM2 boards so users can simply attach a power cell and use the on-board RTC without modifying the device-tree. Cold boot with no cell attached is gracefully handled: VIM2:~ # dmesg | grep rtc [ 7.716150] rtc-hym8563 1-0051: no valid clock/calendar values available [ 7.716957] rtc-hym8563 1-0051: registered as rtc0 [ 7.729850] rtc-hym8563 1-0051: no valid clock/calendar values available [ 7.729877] rtc-hym8563 1-0051: hctosys: unable to read the hardware clock [ 8.126768] rtc-hym8563 1-0051: no valid clock/calendar values available Warm boot (and any boot with cell attached) recalls stored values resulting in consistently faster (re)boot times: VIM2:~ # dmesg | grep rtc [ 7.441671] rtc-hym8563 1-0051: registered as rtc0 [ 7.442663] rtc-hym8563 1-0051: setting system clock to 2020-11-16T05:49:59 UTC (1605505799) Suggested-by: Artem Lapkin <art@khadas.com> Signed-off-by: Christian Hewitt <christianshewitt@gmail.com> Reviewed-by: Neil Armstrong <narmstrong@baylibre.com> Signed-off-by: Kevin Hilman <khilman@baylibre.com> Link: https://lore.kernel.org/r/20201116064147.12062-1-christianshewitt@gmail.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.