Some more Kobo suspend tweaks...

Disable wakeup_count handling, that's often causing more harm than
anything else...
Nickel doesn't even use it, that should have been a hint ;).

Make the logging slightly less confusing.
Add commented out debug features (dumping relevant dmesg output).

Re #2188

frontend/device/kobo/device.lua

@@ -268,6 +268,7 @@ function Kobo:suspend()
 end
 
 function Kobo:resume()
+    -- Unflag subsystems for suspend
     os.execute("echo 0 > /sys/power/state-extended")
     -- HACK: wait a bit for the kernel to catch up
     os.execute("sleep 0.1")

platform/kobo/suspend.sh

@@ -1,7 +1,9 @@
 #!/bin/sh
 export PATH="${PATH}:/sbin:/usr/sbin"
 
-echo "[$(date +'%x @ %X')] Kobo Suspend: BEGIN!"
+echo "[$(date +'%x @ %X')] Kobo Suspend: Going to sleep . . ."
+# NOTE: Sleep as little as possible here, sleeping has a tendency to make everything mysteriously hang...
+
 # Disable wifi
 if lsmod | grep -q sdio_wifi_pwr ; then
 	wlarm_le -i eth0 down
@@ -11,9 +13,23 @@ if lsmod | grep -q sdio_wifi_pwr ; then
 	echo "[$(date +'%x @ %X')] Kobo Suspend: Killed WiFi"
 fi
 
+# Depending on device/FW version, some kernels do not support wakeup_count, account for that
+if [ -e "/sys/power/wakeup_count" ] ; then
+	#HAS_WAKEUP_COUNT="true"
+	# NOTE: ... and of course, it appears to be broken, which probably explains why nickel doesn't use this facility...
+	#	(By broken, I mean that the system wakes up right away).
+	#	So, unless that changes, unconditionally disable it.
+	HAS_WAKEUP_COUNT="false"
+fi
+
+# Clear the kernel ring buffer... (we're missing a proper -C flag...)
+#dmesg -c >/dev/null
+
 # Go to sleep
-current_wakeup_count="$(cat /sys/power/wakeup_count)"
-echo "[$(date +'%x @ %X')] Kobo Suspend: Current WakeUp count: ${current_wakeup_count}"
+if [ "${HAS_WAKEUP_COUNT}" == "true" ] ; then
+	current_wakeup_count="$(cat /sys/power/wakeup_count)"
+	echo "[$(date +'%x @ %X')] Kobo Suspend: Current WakeUp count: ${current_wakeup_count}"
+fi
 echo 1 > /sys/power/state-extended
 # NOTE: Sets gSleep_Mode_Suspend to 1. Used as a flag throughout the kernel to suspend/resume various subsystems
 #       cf. kernel/power/main.c @ L#207
@@ -22,10 +38,14 @@ sleep 2
 echo "[$(date +'%x @ %X')] Kobo Suspend: Waited for 2s because of reasons..."
 sync
 echo "[$(date +'%x @ %X')] Kobo Suspend: Synced FS"
-echo ${current_wakeup_count} > /sys/power/wakeup_count
-echo "[$(date +'%x @ %X')] Kobo Suspend: Wrote WakeUp count: ${current_wakeup_count} ($?)"
+if [ "${HAS_WAKEUP_COUNT}" == "true" ] ; then
+	echo ${current_wakeup_count} > /sys/power/wakeup_count
+	echo "[$(date +'%x @ %X')] Kobo Suspend: Wrote WakeUp count: ${current_wakeup_count} ($?)"
+fi
+echo "[$(date +'%x @ %X')] Kobo Suspend: Asking for a suspend to RAM . . ."
 echo mem > /sys/power/state
-echo "[$(date +'%x @ %X')] Kobo Suspend: Asked to suspend to RAM... ZzZ ZzZ ZzZ? ($?)"
+# NOTE: At this point, we *should* be in suspend to RAM, as such, execution should only resume on wakeup...
+echo "[$(date +'%x @ %X')] Kobo Suspend: ZzZ ZzZ ZzZ? ($?)"
 ## NOTE: Ideally, we'd need a way to warn the user that suspending gloriously failed at this point...
 ##       We can safely assume that just from a non-zero return code, without looking at the detailed stderr message
 ##       (most of the failures we'll see are -EBUSY anyway)
@@ -33,4 +53,16 @@ echo "[$(date +'%x @ %X')] Kobo Suspend: Asked to suspend to RAM... ZzZ ZzZ ZzZ?
 ## which is where the non-sensical 1 -> mem -> 0 loop idea comes from...
 ## cf. nickel_suspend_strace.txt for more details.
 
-echo "[$(date +'%x @ %X')] Kobo Suspend: END! (WakeUp count: $(cat /sys/power/wakeup_count))"
+if [ "${HAS_WAKEUP_COUNT}" == "true" ] ; then
+	echo "[$(date +'%x @ %X')] Kobo Suspend: Woke up! (WakeUp count: $(cat /sys/power/wakeup_count))"
+else
+	echo "[$(date +'%x @ %X')] Kobo Suspend: Woke up!"
+fi
+
+# Print tke kernel log since our attempt to sleep...
+#dmesg -c
+
+# Now that we're up, unflag subsystems for suspend...
+# NOTE: We do that in Kobo:resume() to keep things tidy and easier to follow
+#echo 0 > /sys/power/state-extended
+#echo "[$(date +'%x @ %X')] Kobo Suspend: Unflagged kernel subsystems for suspend"