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When a 400KHz freq is used on this model of ELAN touchpad in Linux, excessive smoothing (similar to when the touchpad's firmware detects a noisy signal) is sometimes applied. As some devices' (e.g, Lenovo V15 G4) ACPI tables specify a 400KHz frequency for this device and some I2C busses (e.g, Designware I2C) default to a 400KHz freq, force the speed to 100KHz as a workaround. For future investigation: This problem may be related to the default HCNT/LCNT values given by some busses' drivers, because they are not specified in the aforementioned devices' ACPI tables, and because the device works without issues on Windows at what is expected to be a 400KHz frequency. The root cause of the issue is not known. Signed-off-by: Randolph Ha <rha051117@gmail.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.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 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.