[Kobo] Don't send a flood a FrontlightStateChanged events during the FL ramps (#6667)

* Only send a single FrontlightStateChanged event on toggle

Prevents the ReaderFooter refresh from going wonky

frontend/device/generic/powerd.lua

@@ -141,11 +141,11 @@ function BasePowerD:isCharging()
     return self:isChargingHW()
 end
 
-function BasePowerD:_setIntensity(intensity)
+function BasePowerD:_setIntensity(intensity, silent)
     self:setIntensityHW(intensity)
-    -- BasePowerD is loaded before UIManager. So we cannot broadcast events before UIManager has
-    -- been loaded.
-    if package.loaded["ui/uimanager"] ~= nil then
+    -- BasePowerD is loaded before UIManager. So we cannot broadcast events before UIManager has been loaded.
+    -- NOTE: If silent is set, inhibit the Event (useful for platforms that do a ramp-up/ramp-down on toggle).
+    if not silent and package.loaded["ui/uimanager"] ~= nil then
         local Event = require("ui/event")
         local UIManager = require("ui/uimanager")
         UIManager:broadcastEvent(Event:new("FrontlightStateChanged"))

frontend/device/kobo/powerd.lua

@@ -327,7 +327,8 @@ function KoboPowerD:turnOffFrontlightHW()
     end
     ffiUtil.runInSubProcess(function()
         for i = 1,5 do
-            self:_setIntensity(math.floor(self.fl_intensity - ((self.fl_intensity / 5) * i)))
+            -- NOTE: Make sure _setIntensity doesn't send a FrontlightStateChanged event for those!
+            self:_setIntensity(math.floor(self.fl_intensity - ((self.fl_intensity / 5) * i)), true)
             --- @note: Newer devices appear to block slightly longer on FL ioctls/sysfs, so only sleep on older devices,
             ---        otherwise we get a jump and not a ramp ;).
             if not self.device:hasNaturalLight() then
@@ -366,7 +367,8 @@ function KoboPowerD:turnOnFrontlightHW()
     end
     ffiUtil.runInSubProcess(function()
         for i = 1,5 do
-            self:_setIntensity(math.ceil(self.fl_min + ((self.fl_intensity / 5) * i)))
+            -- NOTE: Make sure _setIntensity doesn't send a FrontlightStateChanged event for those!
+            self:_setIntensity(math.ceil(self.fl_min + ((self.fl_intensity / 5) * i)), true)
             --- @note: Newer devices appear to block slightly longer on FL ioctls/sysfs, so only sleep on older devices,
             ---        otherwise we get a jump and not a ramp ;).
             if not self.device:hasNaturalLight() then