backport: HID: wacom: Lazy-init batteries

Rather than creating batteries as part of the initial device probe, let's
make the process lazy. This gives us the opportunity to prevent batteries
from being created in situations where they are unnecessary.

There are two cases in particular where batteries are being unnecessarily
created at initialization. These are AES sensors (for which we don't know
any battery status information until a battery-powered pen actually comes
into prox) peripheral tablets which share HID descriptors between the
wired-only and wireless-capable SKUs of a family of devices.

This patch will delay battery initialization of the former until a pen
actually comes into prox. It will delay battery initialization of the
latter until either a pen comes into prox or a "heartbeat" packet is
processed.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217062
Link: https://gitlab.gnome.org/GNOME/gnome-control-center/-/issues/2354
Signed-off-by: Jason Gerecke <[email protected]>
Tested-by: Mario Limonciello <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>
[[email protected]: Imported into input-wacom (7fc68653fc2e)]
Signed-off-by: Jason Gerecke <[email protected]>
[[email protected]: Backported form input-wacom (c6c30f5)]
Signed-off-by: Jason Gerecke <[email protected]>

Author: jigpu

3.17/wacom_sys.c

@@ -2265,13 +2265,6 @@ static int wacom_parse_and_register(struct wacom *wacom, bool wireless)
 	if (error)
 		goto fail_shared_data;
 
-	if (!(features->device_type & WACOM_DEVICETYPE_WL_MONITOR) &&
-	     (features->quirks & WACOM_QUIRK_BATTERY)) {
-		error = wacom_initialize_battery(wacom);
-		if (error)
-			goto fail_battery;
-	}
-
 	error = wacom_register_inputs(wacom);
 	if (error)
 		goto fail_register_inputs;
@@ -2331,7 +2324,6 @@ static int wacom_parse_and_register(struct wacom *wacom, bool wireless)
 #ifndef WACOM_POWERSUPPLY_41
 	wacom_destroy_battery(wacom);
 #endif
-fail_battery:
 fail_shared_data:
 fail_parsed:
 fail_allocate_inputs:
@@ -2417,9 +2409,6 @@ static void wacom_wireless_work(struct work_struct *work)
 
 		strlcpy(wacom_wac->name, wacom_wac1->name,
 			sizeof(wacom_wac->name));
-		error = wacom_initialize_battery(wacom);
-		if (error)
-			goto fail;
 	}
 
 	return;

3.17/wacom_wac.c

@@ -126,6 +126,11 @@ static void wacom_notify_battery(struct wacom_wac *wacom_wac,
 	bool bat_connected, bool ps_connected)
 {
 	struct wacom *wacom = container_of(wacom_wac, struct wacom, wacom_wac);
+	bool bat_initialized = WACOM_POWERSUPPLY_DEVICE(wacom->battery.battery);
+	bool has_quirk = wacom_wac->features.quirks & WACOM_QUIRK_BATTERY;
+
+	if (bat_initialized != has_quirk)
+		wacom_schedule_work(wacom_wac, WACOM_WORKER_BATTERY);
 
 	__wacom_notify_battery(&wacom->battery, bat_status, bat_capacity,
 			       bat_charging, bat_connected, ps_connected);
@@ -3389,19 +3394,13 @@ static int wacom_status_irq(struct wacom_wac *wacom_wac, size_t len)
 		int battery = (data[8] & 0x3f) * 100 / 31;
 		bool charging = !!(data[8] & 0x80);
 
+		features->quirks |= WACOM_QUIRK_BATTERY;
 		wacom_notify_battery(wacom_wac, WACOM_POWER_SUPPLY_STATUS_AUTO,
 				     battery, charging, battery || charging, 1);
-
-		if (!WACOM_POWERSUPPLY_DEVICE(wacom->battery.battery) &&
-		    !(features->quirks & WACOM_QUIRK_BATTERY)) {
-			features->quirks |= WACOM_QUIRK_BATTERY;
-			wacom_schedule_work(wacom_wac, WACOM_WORKER_BATTERY);
-		}
 	}
 	else if ((features->quirks & WACOM_QUIRK_BATTERY) &&
 		 WACOM_POWERSUPPLY_DEVICE(wacom->battery.battery)) {
 		features->quirks &= ~WACOM_QUIRK_BATTERY;
-		wacom_schedule_work(wacom_wac, WACOM_WORKER_BATTERY);
 		wacom_notify_battery(wacom_wac, POWER_SUPPLY_STATUS_UNKNOWN, 0, 0, 0, 0);
 	}
 	return 0;