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media: add tuner standby op, use where needed

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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>
This commit is contained in:
Hans Verkuil
2018-02-21 02:49:25 -05:00
committed by Mauro Carvalho Chehab
parent 3f97df91a1
commit 3aab15af9a
13 changed files with 28 additions and 66 deletions
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4
include/media/v4l2-subdev.h
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@@ -224,6 +224,9 @@ struct v4l2_subdev_core_ops {
* struct v4l2_subdev_tuner_ops - Callbacks used when v4l device was opened
* in radio mode.
*
* @standby: puts the tuner in standby mode. It will be woken up
* automatically the next time it is used.
*
* @s_radio: callback that switches the tuner to radio mode.
* drivers should explicitly call it when a tuner ops should
* operate on radio mode, before being able to handle it.
@@ -268,6 +271,7 @@ struct v4l2_subdev_core_ops {
* }
*/
struct v4l2_subdev_tuner_ops {
int (*standby)(struct v4l2_subdev *sd);
int (*s_radio)(struct v4l2_subdev *sd);
int (*s_frequency)(struct v4l2_subdev *sd, const struct v4l2_frequency *freq);
int (*g_frequency)(struct v4l2_subdev *sd, struct v4l2_frequency *freq);