py: Add CameraManager.read_event()

Add CameraManager.read_event() so that the user does not need to call
os.read().

We use eventfd, and we must always read 8 bytes. Hiding that inside
read_event() makes sense.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/py/cam/cam.py

@@ -9,7 +9,6 @@
 import argparse
 import binascii
 import libcamera as libcam
-import os
 import sys
 import traceback
 
@@ -294,7 +293,7 @@ def event_handler(state):
         cm = state['cm']
         contexts = state['contexts']
 
-        os.read(cm.efd, 8)
+        cm.read_event()
 
         reqs = cm.get_ready_requests()