From a97fcf19ecd2d73def84fc60d206372883599631 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?George=20Bi=C8=99oc?= <george.bisoc@reactos.org>
Date: Fri, 10 Jan 2025 22:23:23 +0100
Subject: [PATCH] [CMBATT] Minor improvements to estimated battery time code

- Declare CMBATT_DISCHARGE_TIME and CMBATT_CAPACITY_BOGUS constructs
- Determine if the battery was already discharging and if not, update the time when it's being discharged
- Fix the condition where it checks if the battery has been discharging for quite some time
- Default the time to BATTERY_UNKNOWN_TIME if querying the estimated battery time request fails or if the battery has just started discharging not over 15 seconds

CORE-18969
CORE-19452
---
 drivers/bus/acpi/cmbatt/cmbatt.c | 21 ++++++++++++++++-----
 drivers/bus/acpi/cmbatt/cmbatt.h | 12 ++++++++++++
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/drivers/bus/acpi/cmbatt/cmbatt.c b/drivers/bus/acpi/cmbatt/cmbatt.c
index 407fa149572..dd01f8b22be 100644
--- a/drivers/bus/acpi/cmbatt/cmbatt.c
+++ b/drivers/bus/acpi/cmbatt/cmbatt.c
@@ -1085,6 +1085,7 @@ CmBattGetBatteryStatus(IN PCMBATT_DEVICE_EXTENSION DeviceExtension,
 {
     ULONG PsrData = 0;
     NTSTATUS Status;
+    BOOLEAN WasDischarging;
     ULONG BstState;
     ULONG PowerUnit;
     ULONG DesignVoltage, PresentRate, RemainingCapacity;
@@ -1113,6 +1114,9 @@ CmBattGetBatteryStatus(IN PCMBATT_DEVICE_EXTENSION DeviceExtension,
         return Status;
     }
 
+    /* Remember if the battery was discharging at the time of querying new status */
+    WasDischarging = !!(DeviceExtension->State & BATTERY_DISCHARGING);
+
     /* Clear current BST information */
     DeviceExtension->State = 0;
     DeviceExtension->RemainingCapacity = 0;
@@ -1135,9 +1139,9 @@ CmBattGetBatteryStatus(IN PCMBATT_DEVICE_EXTENSION DeviceExtension,
     {
         /* Set power state and check if it just started discharging now */
         DeviceExtension->State |= BATTERY_DISCHARGING;
-        if (!(DeviceExtension->State & ACPI_BATT_STAT_DISCHARG))
+        if (!WasDischarging)
         {
-            /* Remember the time when the state changed */
+            /* The battery is discharging now and not before, remember the time when the state changed */
             DeviceExtension->InterruptTime = KeQueryInterruptTime();
         }
     }
@@ -1363,8 +1367,8 @@ CmBattQueryInformation(IN PCMBATT_DEVICE_EXTENSION FdoExtension,
 
         case BatteryEstimatedTime:
 
-            /* Check if it's been more than 2 1/2 minutes since the last change */
-            if ((KeQueryInterruptTime() - 150000000) > (FdoExtension->InterruptTime))
+            /* Check if it's been more than 15 seconds since the last change */
+            if (KeQueryInterruptTime() > (FdoExtension->InterruptTime + CMBATT_DISCHARGE_TIME))
             {
                 /* Get new battery status */
                 CmBattGetBatteryStatus(FdoExtension, FdoExtension->Tag);
@@ -1379,6 +1383,9 @@ CmBattQueryInformation(IN PCMBATT_DEVICE_EXTENSION FdoExtension,
                 /* Grab the remaining capacity */
                 RemainingCapacity = FdoExtension->RemainingCapacity;
 
+                /* Default time to unknown if we fail the request later */
+                RemainingTime = BATTERY_UNKNOWN_TIME;
+
                 /* See if we don't know one or the other */
                 if ((Rate == BATTERY_UNKNOWN_RATE) ||
                     (RemainingCapacity == BATTERY_UNKNOWN_CAPACITY))
@@ -1410,7 +1417,7 @@ CmBattQueryInformation(IN PCMBATT_DEVICE_EXTENSION FdoExtension,
                 else
                 {
                     /* We have data, but is it valid? */
-                    if (RemainingCapacity > 0x123456)
+                    if (RemainingCapacity > CMBATT_CAPACITY_BOGUS)
                     {
                         /* The capacity seems bogus, so don't use it */
                         if (CmBattDebug & CMBATT_ACPI_WARNING)
@@ -1423,6 +1430,10 @@ CmBattQueryInformation(IN PCMBATT_DEVICE_EXTENSION FdoExtension,
                     }
                 }
             }
+            else
+            {
+                RemainingTime = BATTERY_UNKNOWN_TIME;
+            }
 
             /* Return the remaining time */
             QueryData = &RemainingTime;
diff --git a/drivers/bus/acpi/cmbatt/cmbatt.h b/drivers/bus/acpi/cmbatt/cmbatt.h
index e6ab5f029bd..4a2ec81acd3 100644
--- a/drivers/bus/acpi/cmbatt/cmbatt.h
+++ b/drivers/bus/acpi/cmbatt/cmbatt.h
@@ -42,6 +42,18 @@
 #define CMBATT_PNP_ENTRY_EXIT   0x200
 #define CMBATT_ACPI_ASSERT      0x400
 
+//
+// Constant used to determine if the battery was discharging
+// for over 15 seconds since last time the AC adapter got unplugged.
+//
+#define CMBATT_DISCHARGE_TIME   150000000
+
+//
+// Bogus constant used to determine if the remaining battery capacity
+// overflows which is returned by the hardware.
+//
+#define CMBATT_CAPACITY_BOGUS   0x100000
+
 typedef enum _CMBATT_EXTENSION_TYPE
 {
     CmBattAcAdapter,