media: docs-rst: Clarify duration of LP-11 mode

Add a sentence that makes it more clear when the CSI-2 transmitter
must, if possible, exit LP-11 mode. That is, maintain LP-11 mode
until stream on, at which point the transmitter activates the clock
lane and transition to HS mode.
Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/media/kapi/csi2.rst

@@ -49,9 +49,13 @@ where
 
 The transmitter drivers must, if possible, configure the CSI-2
 transmitter to *LP-11 mode* whenever the transmitter is powered on but
-not active. Some transmitters do this automatically but some have to
-be explicitly programmed to do so, and some are unable to do so
-altogether due to hardware constraints.
+not active, and maintain *LP-11 mode* until stream on. Only at stream
+on should the transmitter activate the clock on the clock lane and
+transition to *HS mode*.
+
+Some transmitters do this automatically but some have to be explicitly
+programmed to do so, and some are unable to do so altogether due to
+hardware constraints.
 
 Stopping the transmitter
 ^^^^^^^^^^^^^^^^^^^^^^^^