AutoSuspend: Some more fixes & cleanups (#9263)

* AutoSuspend: Use the canSuspend devcap check instead of reinventing the wheel.
* Device & UIManager: Cleanup canSuspend devcap check related stuff to avoid boilerplate code.
  (It also now defaults to no, and is explicitly set by device implementations where supported).
* AutoSuspend: Re-engage suspend/shutdown timers when fully charged.
  This restores the existing behavior pre #9036
  (c.f., https://github.com/koreader/koreader/pull/9258#issuecomment-1167672356)
* SDL: Unbreak the fake suspend behavior so that it actually works.
  Tweak the default screensaver message to remind users that Power is bound to F2.
  (Fix #9262)
* AutoSuspend: Re-engage suspend/shutdown timers on unplug.
  This matters on Kobo, because the unexpected wakeup guard might have stopped the suspend timer.

frontend/device/cervantes/device.lua

@@ -48,6 +48,7 @@ local Cervantes = Generic:new{
     hasWifiManager = yes,
     canReboot = yes,
     canPowerOff = yes,
+    canSuspend = yes,
     home_dir = "/mnt/public",
 
     -- do we support usb mass storage?

frontend/device/generic/device.lua

@@ -68,7 +68,7 @@ local Device = {
     canToggleChargingLED = no,
     canUseWAL = yes, -- requires mmap'ed I/O on the target FS
     canRestart = yes,
-    canSuspend = yes,
+    canSuspend = no,
     canStandby = no,
     canPowerSaveWhileCharging = no,
     total_standby_time = 0, -- total time spent in standby

frontend/device/kindle/device.lua

@@ -133,6 +133,8 @@ local Kindle = Generic:new{
     canModifyFBInfo = yes,
     -- NOTE: Newer devices will turn the frontlight off at 0
     canTurnFrontlightOff = yes,
+    -- NOTE: Via powerd.toggleSuspend
+    canSuspend = yes,
     home_dir = "/mnt/us",
     -- New devices are REAGL-aware, default to REAGL
     isREAGL = yes,

frontend/device/kobo/device.lua

@@ -72,6 +72,7 @@ local Kobo = Generic:new{
     canStandby = no, -- will get updated by checkStandby()
     canReboot = yes,
     canPowerOff = yes,
+    canSuspend = yes,
     -- most Kobos have X/Y switched for the touch screen
     touch_switch_xy = true,
     -- most Kobos have also mirrored X coordinates
@@ -1076,6 +1077,11 @@ function Kobo:resume()
     self:setupChargingLED()
 end
 
+function Kobo:usbPlugOut()
+    -- Reset the unexpected wakeup shenanigans, since we're no longer charging, meaning power savings are now critical again ;).
+    self.unexpected_wakeup_count = 0
+end
+
 function Kobo:saveSettings()
     -- save frontlight state to G_reader_settings (and NickelConf if needed)
     self.powerd:saveSettings()

frontend/device/remarkable/device.lua

@@ -37,6 +37,7 @@ local Remarkable = Generic:new{
     hasOTAUpdates = yes,
     canReboot = yes,
     canPowerOff = yes,
+    canSuspend = yes,
     isTouchDevice = yes,
     hasFrontlight = no,
     hasSystemFonts = yes,

frontend/device/sdl/device.lua

@@ -67,7 +67,7 @@ local Device = Generic:new{
     hasEinkScreen = no,
     hasSystemFonts = yes,
     canSuspend = no,
-    canStandby = yes,
+    canStandby = no,
     startTextInput = SDL.startTextInput,
     stopTextInput = SDL.stopTextInput,
     canOpenLink = getLinkOpener,
@@ -120,9 +120,12 @@ local Emulator = Device:new{
     hasNaturalLightApi = yes,
     hasWifiToggle = yes,
     hasWifiManager = yes,
+    -- Not really, Device:reboot & Device:powerOff are not implemented, so we just exit ;).
     canPowerOff = yes,
     canReboot = yes,
+    -- NOTE: Via simulateSuspend
     canSuspend = yes,
+    canStandby = no,
 }
 
 local UbuntuTouch = Device:new{
@@ -337,11 +340,13 @@ function Emulator:simulateSuspend()
     local Screensaver = require("ui/screensaver")
     Screensaver:setup()
     Screensaver:show()
+    self.screen_saver_mode = true
 end
 
 function Emulator:simulateResume()
     local Screensaver = require("ui/screensaver")
     Screensaver:close()
+    self.screen_saver_mode = false
 end
 
 -- fake network manager for the emulator

frontend/device/sony-prstux/device.lua

@@ -17,6 +17,7 @@ local SonyPRSTUX = Generic:new{
     hasWifiManager = yes,
     canReboot = yes,
     canPowerOff = yes,
+    canSuspend = yes,
     usbPluggedIn = false,
     home_dir = nil,
 }

frontend/ui/screensaver.lua

@@ -64,6 +64,11 @@ local Screensaver = {
     default_screensaver_message = _("Sleeping"),
 }
 
+-- Remind emulator users that Power is bound to F2
+if Device:isEmulator() then
+    Screensaver.default_screensaver_message = Screensaver.default_screensaver_message .. "\n" .. _("(Press F2 to resume)")
+end
+
 function Screensaver:_getRandomImage(dir)
     if not dir then
         return nil

frontend/ui/uimanager.lua

@@ -173,6 +173,7 @@ function UIManager:init()
         self.event_handlers["Light"] = function()
             Device:getPowerDevice():toggleFrontlight()
         end
+        -- USB plug events with a power-only charger
         self.event_handlers["Charging"] = function()
             self:_beforeCharging()
             -- NOTE: Plug/unplug events will wake the device up, which is why we put it back to sleep.
@@ -182,11 +183,13 @@ function UIManager:init()
         end
         self.event_handlers["NotCharging"] = function()
             -- We need to put the device into suspension, other things need to be done before it.
+            Device:usbPlugOut()
             self:_afterNotCharging()
             if Device.screen_saver_mode then
                 self:suspend()
             end
         end
+        -- USB plug events with a data-aware host
         self.event_handlers["UsbPlugIn"] = function()
             self:_beforeCharging()
             -- NOTE: Plug/unplug events will wake the device up, which is why we put it back to sleep.
@@ -200,6 +203,7 @@ function UIManager:init()
         end
         self.event_handlers["UsbPlugOut"] = function()
             -- We need to put the device into suspension, other things need to be done before it.
+            Device:usbPlugOut()
             self:_afterNotCharging()
             if Device.screen_saver_mode then
                 self:suspend()
@@ -382,6 +386,14 @@ function UIManager:init()
             Device:simulateResume()
             self:_afterResume()
         end
+        self.event_handlers["PowerRelease"] = function()
+            -- Resume if we were suspended
+            if Device.screen_saver_mode then
+                self:resume()
+            else
+                self:suspend()
+            end
+        end
     end
 end
 
@@ -1782,11 +1794,11 @@ Executes all the operations of a suspension (i.e., sleep) request.
 This function usually puts the device into suspension.
 ]]
 function UIManager:suspend()
-    if Device:isCervantes() or Device:isKobo() or Device:isSDL() or Device:isRemarkable() or Device:isSonyPRSTUX() then
+    if self.event_handlers["Suspend"] then
         self.event_handlers["Suspend"]()
     elseif Device:isKindle() then
         Device.powerd:toggleSuspend()
-    elseif Device.isPocketBook() and Device.canSuspend() then
+    elseif Device:canSuspend() then
         Device:suspend()
     end
 end
@@ -1801,7 +1813,7 @@ function UIManager:resume()
     -- invalidate the last battery capacity pull time so that we get up to date data immediately.
     Device:getPowerDevice():invalidateCapacityCache()
 
-    if Device:isCervantes() or Device:isKobo() or Device:isSDL() or Device:isRemarkable() or Device:isSonyPRSTUX() then
+    if self.event_handlers["Resume"] then
         self.event_handlers["Resume"]()
     elseif Device:isKindle() then
         self.event_handlers["OutOfSS"]()

plugins/autosuspend.koplugin/main.lua

@@ -1,12 +1,7 @@
 local Device = require("device")
 
-if not Device:isCervantes() and
-    not Device:isKindle() and
-    not Device:isKobo() and
-    not Device:isRemarkable() and
-    not Device:isSDL() and
-    not Device:isSonyPRSTUX() and
-    not Device:isPocketBook() then
+-- If a device can power off or go into standby, it can also suspend ;).
+if not Device:canSuspend() then
     return { disabled = true, }
 end
 
@@ -46,6 +41,7 @@ function AutoSuspend:_enabledStandby()
 end
 
 function AutoSuspend:_enabled()
+    -- NOTE: Plugin is only enabled if Device:canSuspend(), so we can elide the check here
     return self.auto_suspend_timeout_seconds > 0
 end
 
@@ -64,10 +60,11 @@ function AutoSuspend:_schedule(shutdown_only)
     -- On devices with an auxiliary battery, we only care about the auxiliary battery being charged...
     local powerd = Device:getPowerDevice()
     if Device:hasAuxBattery() and powerd:isAuxBatteryConnected() then
-        is_charging = powerd:isAuxCharging()
+        is_charging = powerd:isAuxCharging() and not powerd:isAuxCharged()
     else
-        is_charging = powerd:isCharging()
+        is_charging = powerd:isCharging() and not powerd:isCharged()
     end
+    -- We *do* want to make sure we attempt to go into suspend/shutdown again while *fully* charged, though.
     if PluginShare.pause_auto_suspend or is_charging then
         suspend_delay_seconds = self.auto_suspend_timeout_seconds
         shutdown_delay_seconds = self.autoshutdown_timeout_seconds
@@ -134,8 +131,6 @@ function AutoSuspend:init()
     -- Disabled, until the user opts in.
     self.auto_standby_timeout_seconds = G_reader_settings:readSetting("auto_standby_timeout_seconds", -1)
 
-    if Device:isPocketBook() and not Device:canSuspend() then return end
-
     -- We only want those to exist as *instance* members
     self.is_standby_scheduled = false
     self.going_to_suspend = false
@@ -178,7 +173,6 @@ end
 -- NOTE: event_hook takes care of overloading this to unregister the hook, too.
 function AutoSuspend:onCloseWidget()
     logger.dbg("AutoSuspend: onCloseWidget")
-    if Device:isPocketBook() and not Device:canSuspend() then return end
 
     self:_unschedule()
     self.task = nil
@@ -346,10 +340,21 @@ end
 
 function AutoSuspend:onUnexpectedWakeupLimit()
     logger.dbg("AutoSuspend: onUnexpectedWakeupLimit")
+    -- Should be unnecessary, because we should *always* follow onSuspend, which already does this...
+    -- Better safe than sorry, though ;).
+    self:_unschedule()
     -- Only re-engage the *shutdown* schedule to avoid doing the same dance indefinitely.
     self:_restart()
 end
 
+function AutoSuspend:onNotCharging()
+    logger.dbg("AutoSuspend: onNotCharging")
+    -- Make sure both the suspend & shutdown timers are re-engaged on unplug,
+    -- in case we hit an UnexpectedWakeupLimit during the charge cycle...
+    self:_unschedule()
+    self:_start()
+end
+
 -- time_scale:
 -- 2 ... display day:hour
 -- 1 ... display hour:min
@@ -464,6 +469,7 @@ function AutoSuspend:pickTimeoutValue(touchmenu_instance, title, info, setting,
 end
 
 function AutoSuspend:addToMainMenu(menu_items)
+    -- Device:canSuspend() check elided because it's a plugin requirement
     menu_items.autosuspend = {
         sorting_hint = "device",
         checked_func = function()
@@ -489,7 +495,7 @@ function AutoSuspend:addToMainMenu(menu_items)
                 {60, 24*3600}, 1)
         end,
     }
-    if Device:canPowerOff() or Device:isEmulator() then
+    if Device:canPowerOff() then
         menu_items.autoshutdown = {
             sorting_hint = "device",
             checked_func = function()