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3a4f755124
The USB2.0 OTG PHY of RV1126/1109 which is designed for lower power consumption provides only 8.8mA current source on DM. Multiplied by 45 Ohm host termination resistance, voltage is about 400mV. If the threshold voltage of host is greater than 400mV, the high speed handshake will fail and SoC communicate at full speed. So swing calibration is necessary. We use gpio to control the 220 Ohm pull-up resistor to provide additional current. Experiments show that the voltage of chirpK can be increases to about 600mV. Signed-off-by: Ren Jianing <jianing.ren@rock-chips.com> Change-Id: I387ae1840959540ff9ca22db26896def0e890619
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.