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The v4l2_subdev core s_power op was used for two different things: power on/off sensors or video decoders/encoders and to put a tuner in standby (and only the tuner!). There is no 'tuner wakeup' op, that's done automatically when the tuner is accessed. The danger with calling (s_power, 0) to put a tuner into standby is that it is usually broadcast for all subdevs. So a video receiver subdev that supports s_power will also be powered off, and since there is no corresponding (s_power, 1) they will never be powered on again. In addition, this is specifically meant for tuners only since they draw the most current. This patch adds a new tuner op called 'standby' and replaces all calls to (core, s_power, 0) by (tuner, standby). This prevents confusion between the two uses of s_power. Note that there is no overlap: bridge drivers either just want to put the tuner into standby, or they deal with powering on/off sensors. Never both. This also makes it easier to replace s_power for the remaining bridge drivers with some PM code later. Whether we want something cleaner for tuners in the future is a separate topic. There is a lot of legacy code surrounding tuners, and I am very hesitant about making changes there. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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.