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[ Upstream commit14639a22de] With commit3a6f0fb7b8("regmap: irq: Add support to clear ack registers"), the cpcap interrupts are no longer getting acked properly leading to a very unresponsive device with CPUs fully loaded spinning in the threaded IRQ handlers. To me it looks like the clear_ack commit above actually fixed a long standing bug in regmap_irq_thread() where we unconditionally acked the interrupts earlier without considering ack_invert. And the issue with cpcap started happening as we now also consider ack_invert. Tim Harvey <tharvey@gateworks.com> tried to fix this issue earlier with "[PATCH v2] regmap: irq: fix ack-invert", but the reading of the ack register was considered unnecessary for just ack_invert, and we did not have clear_ack available yet. As the cpcap irqs worked both with and without ack_invert earlier because of the unconditional ack, the problem remained hidden until now. Also, looks like the earlier v3.0.8 based Motorola Android Linux kernel does clear_ack style read-clear-write with "ireg_val & ~mreg_val" instead of just ack_invert style write. So let's switch cpcap to use clear_ack to fix the issue. Fixes:3a6f0fb7b8("regmap: irq: Add support to clear ack registers") Cc: Carl Philipp Klemm <philipp@uvos.xyz> Cc: Laxminath Kasam <lkasam@codeaurora.org> Cc: Merlijn Wajer <merlijn@wizzup.org> Cc: Mark Brown <broonie@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Sebastian Reichel <sre@kernel.org> Cc: Tim Harvey <tharvey@gateworks.com> Signed-off-by: Tony Lindgren <tony@atomide.com> Tested-by: Pavel Machek <pavel@ucw.cz> Reviewed-By: Tim Harvey <tharvey@gateworks.com> Signed-off-by: Lee Jones <lee.jones@linaro.org> 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.