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8c51521de1
Increase the frequency of the PWM signal that drives the LED backlight of
the Pinebook Pro's panel, from about 1.35 KHz (which equals to the PWM
period of 740,740 ns), to exactly 8 kHz (which equals to the PWM period of
125,000 ns). Using a higher PWM frequency for the panel backlight, which
reduces the flicker, can only be beneficial to the end users' eyes.
On top of that, increasing the backlight PWM signal frequency reportedly
eliminates the buzzing emitted from the Pinebook Pro's built-in speakers
when certain backlight levels are set, which cause some weird interference
with some of the components of the Pinebook Pro's audio chain.
The old value for the backlight PWM period, i.e. 740,740 ns, is pretty much
an arbitrary value that was selected during the very early bring-up of the
Pinebook Pro, only because that value seemed to minimize horizontal line
distortion on the display, which resulted from the old X.org drivers causing
screen tearing when dragging windows around. That's no longer an issue, so
there are no reasons to stick with the old PWM period value.
The lower and the upper backlight PWM frequency limits for the Pinebook Pro's
panel, according to its datasheet, are 200 Hz and 10 kHz, respectively. [1]
These changes still leave some headroom, which may have some positive effects
on the lifetime expectancy of the panel's backlight LEDs.
[1] https://files.pine64.org/doc/datasheet/PinebookPro/NV140FHM-N49_Rev.P0_20160804_201710235838.pdf
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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 reStructuredText 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.