676f23eab7
Some power hungry sub-systems like VPU has its own MUs which also use mailbox driver, current mailbox driver uses platform driver model and MU's power will be ON after driver probed and left ON there, it may cause the whole sub-system can NOT enter lower power mode, take VPU driver for example, it has runtime PM support, but due to its MU always ON, the VPU sub-system will be always ON and consume many power during kernel idle. To save power in kernel idle, mailbox driver needs to support runtime PM in order to power off MU when it is unused. However, the runtime suspend/resume can ONLY be implemented in mailbox's .shutdown/.startup callback, so its consumer needs to call mbox_request_channel()/mbox_free_channel() in consumer driver's runtime PM callback, then the MU's power will be ON/OFF along with consumer's runtime PM status. Signed-off-by: Anson Huang <Anson.Huang@nxp.com> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.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.