Kobo: Handle a few PowerCover quirks...

* The first few capacity reads after connecting to the cover may fail

* The PowerCover may trigger spurious move/add usb_plug uevent,
which translate into Charging events for us.
Instead of blindly lighting up the charging LED on those,
check if the device is actually charging, first.

frontend/device/generic/device.lua

@@ -467,6 +467,9 @@ end
 -- Device specific method for toggling the charging LED
 function Device:toggleChargingLED(toggle) end
 
+-- Device specific method for setting the charging LED to the right state
+function Device:setupChargingLED() end
+
 -- Device specific method for enabling a specific amount of CPU cores
 -- (Should only be implemented on embedded platforms where we can afford to control that without screwing with the system).
 function Device:enableCPUCores(amount) end

frontend/device/generic/powerd.lua

@@ -111,6 +111,17 @@ function BasePowerD:read_int_file(file)
     end
 end
 
+function BasePowerD:unchecked_read_int_file(file)
+    local fd = io.open(file, "r")
+    if fd then
+        local int = fd:read("*number")
+        fd:close()
+        return int
+    else
+        return
+    end
+end
+
 function BasePowerD:read_str_file(file)
     local fd = io.open(file, "r")
     if fd then
@@ -160,8 +171,12 @@ function BasePowerD:getAuxCapacity()
     local now_ts = UIManager:getTime()
 
     if (now_ts - self.last_aux_capacity_pull_time):tonumber() >= 60 then
-        self.aux_batt_capacity = self:getAuxCapacityHW()
-        self.last_aux_capacity_pull_time = now_ts
+        local aux_batt_capa = self:getAuxCapacityHW()
+        -- If the read failed, don't update our cache, and retry next time.
+        if aux_batt_capa then
+            self.aux_batt_capacity = aux_batt_capa
+            self.last_aux_capacity_pull_time = now_ts
+        end
     end
     return self.aux_batt_capacity
 end

frontend/device/kobo/device.lua

@@ -387,7 +387,7 @@ local KoboIo = Kobo:new{
     },
 }
 
-function Kobo:_refreshChargingLED()
+function Kobo:setupChargingLED()
     if G_reader_settings:nilOrTrue("enable_charging_led") then
         if self:hasAuxBattery() and self.powerd:isAuxBatteryConnected() then
             self:toggleChargingLED(self.powerd:isAuxCharging())
@@ -512,7 +512,7 @@ function Kobo:init()
     -- We have no way of querying the current state of the charging LED, so, start from scratch.
     -- Much like Nickel, start by turning it off.
     self:toggleChargingLED(false)
-    self:_refreshChargingLED()
+    self:setupChargingLED()
 
     -- Only enable a single core on startup
     self:enableCPUCores(1)
@@ -888,7 +888,7 @@ function Kobo:resume()
     end
 
     -- A full suspend may have toggled the LED off.
-    self:_refreshChargingLED()
+    self:setupChargingLED()
 end
 
 function Kobo:saveSettings()

frontend/device/kobo/powerd.lua

@@ -100,7 +100,9 @@ function KoboPowerD:init()
         self.aux_batt_charging_file = self.aux_battery_sysfs .. "/charge_status" -- "usb_conn" would not allow us to detect the "Full" state
 
         self.getAuxCapacityHW = function(this)
-            return this:read_int_file(this.aux_batt_capacity_file)
+            -- NOTE: The first few reads after connecting to the PowerCover may fail, in which case,
+            --       we pass that detail along to PowerD so that it may retry the call sooner.
+            return this:unchecked_read_int_file(this.aux_batt_capacity_file)
         end
 
         self.isAuxBatteryConnectedHW = function(this)
@@ -110,7 +112,7 @@ function KoboPowerD:init()
         self.isAuxChargingHW = function(this)
             -- 0 when not charging
             -- 3 when full
-            -- 2 when charging via DCP and/or when battery is high (> 70%)
+            -- 2 when charging via DCP
             local charge_status = this:read_int_file(this.aux_batt_charging_file)
             return charge_status ~= 0 and charge_status ~= 3
         end

frontend/ui/uimanager.lua

@@ -1759,17 +1759,15 @@ end
 
 -- The common operations that should be performed when the device is plugged to a power source.
 function UIManager:_beforeCharging()
-    if G_reader_settings:nilOrTrue("enable_charging_led") then
-        Device:toggleChargingLED(true)
-    end
+    -- Leave the kernel some time to figure it out ;o).
+    self:scheduleIn(0.5, function() Device:setupChargingLED() end)
     self:broadcastEvent(Event:new("Charging"))
 end
 
 -- The common operations that should be performed when the device is unplugged from a power source.
 function UIManager:_afterNotCharging()
-    if G_reader_settings:nilOrTrue("enable_charging_led") then
-        Device:toggleChargingLED(false)
-    end
+    -- Leave the kernel some time to figure it out ;o).
+    self:scheduleIn(0.5, function() Device:setupChargingLED() end)
     self:broadcastEvent(Event:new("NotCharging"))
 end