Fix a wait time calculation issue and improve the PR per Pierre's com…

…ments

Co-authored-by: Pierre Equoy <pierre.equoy@canonical.com>

providers/base/bin/lid_close_suspend_open.sh

@@ -1,15 +1,15 @@
 #!/usr/bin/bash
 
 holdoff_timeout_usec=$(gdbus introspect --system --dest org.freedesktop.login1 --object-path /org/freedesktop/login1 -p | grep HoldoffTimeoutUSec | awk '{print $5}' | awk -F\; '{print $1}')
-holdoff_timeout_sec=$(echo "scale=0; $holdoff_timeout_usec / 1000000" | bc)
+holdoff_timeout_sec=$((holdoff_timeout_usec / 1000000))
 
 previous_sleep_log=$(journalctl --output=short-unix --since "$holdoff_timeout_sec seconds ago" -b 0 -r | grep "suspend exit")
 if [[ "$holdoff_timeout_sec" != 0 && "$previous_sleep_log" != "" ]]; then
  # set the previous_sleep_time
  previous_sleep_time=$(echo "$previous_sleep_log" | awk -F'.' '{ print $1 }')
- # sleep a period of time
- sleep_time=$(( $(date +"%s") - "$previous_sleep_time" ))
- echo "sleep for $sleep_time seconds ..."
+ # sleep a period of time. wait_time = holdoff_time - wakeup_time_from_last_suspend
+ sleep_time=$(("$holdoff_timeout_sec" - ($(date +"%s") - "$previous_sleep_time")))
+ echo "DUT was resumed less than ${holdoff_timeout_sec} seconds ago. Waiting for ${sleep_time} seconds before running the test..."
  sleep "$sleep_time"
 fi
 echo "System is ready for suspend test"

providers/base/units/power-management/jobs.pxu

@@ -189,7 +189,7 @@ _steps:
  4. Open the lid
 _verification:
  Did the system suspend when the lid was closed, and resume back when the lid was opened?
- (Note: Systemd will hold off on reacting to lid events in a period of time after system startup or resume. So please make sure the system doesn't just resume from a suspend before run the test.)
+ Note: Systemd will not react to lid events if the DUT was just started or resumed. Please make sure the DUT has been running for long enough before running this test.
 command:
  lid_close_suspend_open.sh
 _summary: Test the functionality of the laptop's lid sensor for suspend/resume actions.