pipeline: raspberrypi: Add a Unicam timeout override config options

Add a new parameter to the pipeline handler config file named
"unicam_timeout_value_ms" to allow users to override the automatically
computed Unicam timeout value.

This value is given in milliseconds, and setting a value of 0 (the
default value) disables the override.

An example use of this parameter would be if an application configured a
RAW stream, and provides buffers for the stream on every request. If the
application holds off on sending requests for a particular reason (e.g.
a timelapse use case), then we will possibly hit the watchdog timeout as
it is only a small multiple of the frame length. This override allows an
application to select a larger value with the knowledge that it may
space requests longer than the calculated timeout value.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/pipeline/raspberrypi/data/example.yaml

@@ -32,6 +32,15 @@
                 # Override any request from the IPA to drop a number of startup
                 # frames.
                 #
-                # "disable_startup_frame_drops": false
+                # "disable_startup_frame_drops": false,
+
+                # Custom timeout value (in ms) for Unicam to use. This overrides
+                # the value computed by the pipeline handler based on frame
+                # durations.
+                #
+                # Set this value to 0 to use the pipeline handler computed
+                # timeout value.
+                #
+                # "unicam_timeout_value_ms": 0,
         }
 }