Fix power button shutdown by consolidating input handling in screen monitor

Both the evtest-based power monitor and the Python screen monitor were
reading /dev/input/event0 simultaneously, causing missed events on the
device's Linux 4.9 kernel. Moved long-press shutdown into the screen
monitor (which already reads event0 directly) and removed the evtest
dependency entirely.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tools/rg35xx-screen-monitor.py

@@ -1,23 +1,27 @@
 #!/usr/bin/env python3
 """
-Screen idle timeout and power button toggle for RG35XX Plus.
+Screen idle timeout, power button toggle, and long-press shutdown for RG35XX Plus.
 
 Monitors /dev/input/event{0,1,2} for activity. Turns off the screen
 (via Allwinner /dev/disp SET_BRIGHTNESS ioctl) after 15s of no input.
 Any button press wakes the screen. A short power button press (<2s)
-toggles the screen on/off.
+toggles the screen on/off. A long press (3s+) triggers clean shutdown.
 
 Launched by rg35xx-wrapper.sh alongside sdlamp2. Killed on cleanup.
+
+Usage: rg35xx-screen-monitor.py <sdlamp2_pid>
 """
 import fcntl
 import os
+import select
 import signal
 import struct
 import sys
 import time
 
 IDLE_TIMEOUT = 15  # seconds
-POWER_HOLD_THRESHOLD = 2.0  # seconds — short press if released before this
+POWER_SHORT_THRESHOLD = 2.0  # seconds — short press if released before this
+POWER_LONG_THRESHOLD = 3.0  # seconds — shutdown if held this long
 
 # Allwinner /dev/disp ioctl commands
 DISP_GET_BRIGHTNESS = 0x103
@@ -50,6 +54,12 @@ def set_brightness(disp_fd, value):
 
 
 def main():
+    if len(sys.argv) < 2:
+        print("Usage: rg35xx-screen-monitor.py <sdlamp2_pid>", file=sys.stderr)
+        sys.exit(1)
+
+    sdlamp2_pid = int(sys.argv[1])
+
     disp_fd = os.open("/dev/disp", os.O_RDWR)
     original_brightness = get_brightness(disp_fd)
     if original_brightness == 0:
@@ -82,14 +92,29 @@ def main():
         os.close(disp_fd)
         sys.exit(1)
 
-    import select
-
     while True:
-        readable, _, _ = select.select(event_fds, [], [], IDLE_TIMEOUT)
+        # Dynamic timeout: if power button is held, shorten timeout to detect 3s mark
+        timeout = IDLE_TIMEOUT
+        if power_press_time is not None:
+            remaining = POWER_LONG_THRESHOLD - (time.monotonic() - power_press_time)
+            if remaining <= 0:
+                # Already past threshold — trigger shutdown now
+                touch_and_shutdown(disp_fd, original_brightness, screen_on, sdlamp2_pid)
+                return
+            timeout = min(timeout, remaining)
+
+        readable, _, _ = select.select(event_fds, [], [], timeout)
+
+        # Check long-press threshold (whether select returned due to timeout or input)
+        if power_press_time is not None:
+            held = time.monotonic() - power_press_time
+            if held >= POWER_LONG_THRESHOLD:
+                touch_and_shutdown(disp_fd, original_brightness, screen_on, sdlamp2_pid)
+                return
 
         if not readable:
-            # Timeout — no input for IDLE_TIMEOUT seconds
-            if screen_on:
+            # Timeout with no input — turn off screen if idle
+            if screen_on and power_press_time is None:
                 set_brightness(disp_fd, 0)
                 screen_on = False
             continue
@@ -118,7 +143,7 @@ def main():
                     elif ev_value == 0 and power_press_time is not None:  # release
                         hold_duration = time.monotonic() - power_press_time
                         power_press_time = None
-                        if hold_duration < POWER_HOLD_THRESHOLD:
+                        if hold_duration < POWER_SHORT_THRESHOLD:
                             # Short press — toggle screen
                             if screen_on:
                                 set_brightness(disp_fd, 0)
@@ -126,6 +151,7 @@ def main():
                             else:
                                 set_brightness(disp_fd, original_brightness)
                                 screen_on = True
+                        # Between SHORT and LONG threshold: ignore (release before 3s)
                     continue
 
                 # Any other key press — wake screen if off
@@ -134,5 +160,20 @@ def main():
                     screen_on = True
 
 
+def touch_and_shutdown(disp_fd, original_brightness, screen_on, sdlamp2_pid):
+    """Signal sdlamp2 to exit and flag for shutdown."""
+    if not screen_on:
+        set_brightness(disp_fd, original_brightness)
+    os.close(disp_fd)
+    try:
+        open("/tmp/.sdlamp2_shutdown", "w").close()
+    except OSError:
+        pass
+    try:
+        os.kill(sdlamp2_pid, signal.SIGTERM)
+    except OSError:
+        pass
+
+
 if __name__ == "__main__":
     main()