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Some of the ADCs by Analog signal their irq condition on the MISO line. So typically that line is connected to an SPI controller and a GPIO. The GPIO is used as input and the respective interrupt is enabled when the last SPI transfer is completed. Depending on the GPIO controller the toggling MISO line might make the interrupt pending even while it's masked. In that case the irq handler is called immediately after irq_enable() and so before the device actually pulls that line low which results in non-sense values being reported to the upper layers. The only way to find out if the line was actually pulled low is to read the GPIO. (There is a flag in AD7124's status register that also signals if an interrupt was asserted, but reading that register toggles the MISO line and so might trigger another spurious interrupt.) Add the possibility to specify an interrupt GPIO in the machine description in addition to the plain interrupt. This GPIO is used then to check if the irq line is actually active in the irq handler. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com> Link: https://patch.msgid.link/5be9a4cc4dc600ec384c88db01dd661a21506b9c.1733504533.git.u.kleine-koenig@baylibre.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.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 reStructuredText 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.