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On Asus laptop models X505BA, X505BP, X542BA and X542BP, the i2c-hid touchpad (using a GPIO for interrupts) becomes unresponsive after a few minutes of usage, or after placing two fingers on the touchpad, which seems to have the effect of queuing up a large amount of input data to be transferred. When the touchpad is in unresponsive state, we observed that the GPIO level-triggered interrupt is still at it's active level, however the pinctrl-amd driver is not receiving/dispatching more interrupts at this point. After the initial interrupt arrives, amd_gpio_irq_mask() is called however we then see amd_gpio_irq_handler() being called repeatedly for the same irq; the interrupt mask is not taking effect because of the following sequence of events: - amd_gpio_irq_handler fires, reads and caches pin reg - amd_gpio_irq_handler calls generic_handle_irq() - During IRQ handling, amd_gpio_irq_mask() is called and modifies pin reg - amd_gpio_irq_handler clears interrupt by writing cached value The stale cached value written at the final stage undoes the masking. Fix this by re-reading the register before clearing the interrupt. I also spotted that the interrupt-clearing code can race against amd_gpio_irq_mask() / amd_gpio_irq_unmask(), so add locking there. Presumably this race was leading to the loss of interrupts. After these changes, the touchpad appears to be working fine. Signed-off-by: Daniel Drake <drake@endlessm.com> Acked-by: Shah, Nehal-bakulchandra <Nehal-Bakulchandra.shah@amd.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.