Fork of Freescale Linux kernel for reMarkable2 https://github.com/Freescale/linux-fslc
104dc5e20f
It quite often is necessary to resume devices from runtime suspend during system suspend for various reasons (for example, if their wakeup settings need to be changed), but that requires middle-layer or subsystem code to follow additional rules which currently are not clearly documented. Namely, if a driver calls pm_runtime_resume() for the device from its ->suspend (or equivalent) system sleep callback, that may not work if the middle layer above it has updated the state of the device from its ->prepare or ->suspend callbacks already in an incompatible way. For this reason, all middle layers must follow the rule that, until the ->suspend callback provided by the device's driver is invoked, the only way in which the device's state can be updated is by calling pm_runtime_resume() for it, if necessary. Fortunately enough, all middle layers in the code base today follow this rule, but it is not explicitly stated anywhere, so do that. Note that calling pm_runtime_resume() from the ->suspend callback of a driver will cause the ->runtime_resume callback provided by the middle layer to be invoked, but the rule above guarantees that this callback will nest properly with the middle layer's ->suspend callback and it will play well with the ->prepare one invoked before. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> |
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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.