ACE is a submodule of IVSC which controls camera sensor's
ownership, belonging to host or IVSC. When IVSC owns camera
sensor, it is for algorithm computing. When host wants to
control camera sensor, ACE module needs to be informed of
ownership with defined interface.
The interface is via MEI. There is a separate MEI UUID, which
this driver uses to enumerate.
To switch ownership of camera sensor between IVSC and host,
the caller specifies the defined ownership information which
will be sent to firmware by sending MEI command.
Device link(device_link_add) is used to set the right camera
sensor ownership before accessing the sensor via I2C. With
DL_FLAG_PM_RUNTIME and DL_FLAG_RPM_ACTIVE, the supplier device
will be PM runtime resumed before the consumer(camera sensor).
So use runtime PM callbacks to transfer the ownership between
host and IVSC.
Signed-off-by: Wentong Wu <wentong.wu@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
CSI is a submodule of IVSC which can route camera sensor data
to the outbound MIPI CSI-2 interface.
The interface communicating with firmware is via MEI. There is
a separate MEI UUID, which this driver uses to enumerate.
To route camera sensor data to host, the information of link
frequency and number of data lanes is sent to firmware by
sending MEI command when starting stream.
CSI also provides a privacy mode. When privacy mode is turned
on, camera sensor can't be used. This means that both IVSC and
host Image Processing Unit(IPU) can't get image data. And when
this mode is turned on, user is notified via v4l2 control
callback.
Link: https://lore.kernel.org/linux-media/20230803115550.1601965-2-sakari.ailus@linux.intel.com
Signed-off-by: Wentong Wu <wentong.wu@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
