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Some platforms have the capability to configure the performance state of PM domains. This patch enhances the genpd core to support such platforms. The performance levels (within the genpd core) are identified by positive integer values, a lower value represents lower performance state. This patch adds a new genpd API, which is called by user drivers (like OPP framework): - int dev_pm_genpd_set_performance_state(struct device *dev, unsigned int state); This updates the performance state constraint of the device on its PM domain. On success, the genpd will have its performance state set to a value which is >= "state" passed to this routine. The genpd core calls the genpd->set_performance_state() callback, if implemented, else -ENODEV is returned to the caller. The PM domain drivers need to implement the following callback if they want to support performance states. - int (*set_performance_state)(struct generic_pm_domain *genpd, unsigned int state); This is called internally by the genpd core on several occasions. The genpd core passes the genpd pointer and the aggregate of the performance states of the devices supported by that genpd to this callback. This callback must update the performance state of the genpd (in a platform dependent way). The power domains can avoid supplying above callback, if they don't support setting performance-states. Currently we aren't propagating performance state changes of a subdomain to its masters as we don't have hardware that needs it right now. Over that, the performance states of subdomain and its masters may not have one-to-one mapping and would require additional information. We can get back to this once we have hardware that needs it. Tested-by: Rajendra Nayak <rnayak@codeaurora.org> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> |
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README
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.