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This is a general i2c controller feature. Some I2C devices may need the I2C controller to remain active during resume_noirq() or suspend_noirq(). If the controller is autosuspended, there is no way to wake it up once runtime PM disabled (in suspend_late()). During system resume, the I2C controller will be available only after runtime PM is re-enabled (in resume_early()). However, this may be too late for some devices. Wake up the controller in the suspend() callback while runtime PM is still enabled. The I2C controller will remain available until the suspend_noirq() callback (pm_runtime_force_suspend()) is called. During resume, the I2C controller can be restored by the resume_noirq() callback (pm_runtime_force_resume()). Finally, the resume() callback re-enables autosuspend. As a result, the I2C controller can remain available until the system enters suspend_noirq() and from resume_noirq(). Signed-off-by: Carlos Song <carlos.song@nxp.com> Link: https://lore.kernel.org/r/20241227084736.1323943-1-carlos.song@nxp.com Signed-off-by: Andi Shyti <andi.shyti@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 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.