bcfb7ae3f5
Investigation on the AXP803 shows that VBUS_PLUGIN/VBUS_REMOVAL IRQs are triggered on the rising/falling edge of AXP20X_PWR_STATUS_VBUS_USED. The reason IRQs do not arrive while N_VBUSEN/DRIVEVBUS is high is because AXP20X_PWR_STATUS_VBUS_USED also never goes high. This also means that if VBUS is online, a VBUS_REMOVAL IRQ is received immediately on setting N_VBUSEN/DRIVEVBUS high (and VBUS_PLUGIN shortly after it is set back low). This was also verified to be the case when manually offlining VBUS through AXP20X_VBUS_PATH_SELECT. As long as VBUS is online, a present->absent transition necessarily implies an online->offline transition. Since will cause an IRQ, there is no need to poll while VBUS is online. To ensure the driver's view of VBUS online status remains accurate, unconditionally poll once when receiving an IRQ and when resuming. If VBUS is still online at that time, polling will cease until the next VBUS_REMOVAL IRQ. Reviewed-by: Chen-Yu Tsai <wens@csie.org> Signed-off-by: Samuel Holland <samuel@sholland.org> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.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.