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[ Upstream commit 5ac121b81b4051e7fc83d5b3456a5e499d5bd147 ] The AXP288's recommended and factory default Vhold value (minimum input voltage below which the input current draw will be reduced) is 4.4V. This lines up with other charger IC's such as the TI bq2419x/bq2429x series which use 4.36V or 4.44V. For some reason some BIOS-es initialize Vhold to 4.6V or even 4.7V which combined with the typical voltage drop over typically low wire gauge micro-USB cables leads to the input-current getting capped below 1A (with a 2A capable dedicated charger) based on Vhold. This leads to slow charging, or even to the device slowly discharging if the device is in heavy use. As the Linux AXP288 drivers use the builtin BC1.2 charger detection and send the input-current-limit according to the detected charger there really is no reason not to use the recommended 4.4V Vhold. Set Vhold to 4.4V to fix the slow charging issue on various devices. There is one exception, the special-case of the HP X2 2-in-1s which combine this BC1.2 capable PMIC with a Type-C port and a 5V/3A factory provided charger with a Type-C plug which does not do BC1.2. These have their input-current-limit hardcoded to 3A (like under Windows) and use a higher Vhold on purpose to limit the current when used with other chargers. To avoid touching Vhold on these HP X2 laptops the code setting Vhold is added to an else branch of the if checking for these models. Note this also fixes the sofar unused VBUS_ISPOUT_VHOLD_SET_MASK define, which was wrong. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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.