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When cold-booting Asus X434DA, GPIO 7 is found to be already configured as an interrupt, and the GPIO level is found to be in a state that causes the interrupt to fire. As soon as pinctrl-amd probes, this interrupt fires and invokes amd_gpio_irq_handler(). The IRQ is acked, but no GPIO-IRQ handler was invoked, so the GPIO level being unchanged just causes another interrupt to fire again immediately after. This results in an interrupt storm causing this platform to hang during boot, right after pinctrl-amd is probed. Detect this situation and disable the GPIO interrupt when this happens. This enables the affected platform to boot as normal. GPIO 7 actually is the I2C touchpad interrupt line, and later on, i2c-multitouch loads and re-enables this interrupt when it is ready to handle it. Instead of this approach, I considered disabling all GPIO interrupts at probe time, however that seems a little risky, and I also confirmed that Windows does not seem to have this behaviour: the same 41 GPIO IRQs are enabled under both Linux and Windows, which is a far larger collection than the GPIOs referenced by the DSDT on this platform. Signed-off-by: Daniel Drake <drake@endlessm.com> Link: https://lore.kernel.org/r/20190814090540.7152-1-drake@endlessm.com Signed-off-by: Linus Walleij <linus.walleij@linaro.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.