Kernel: Only do i8042 existence check via probing as a fallback

This caused an initialization failure of the i8042 when I tested on
bare metal. We cannot entirely get rid of this method as QEMU for
example doesn't indicate the existence of an i8042 via ACPI, but we can
get away with only doing the manual probing if ACPI is disabled or we
didn't get a 'yes' from it.
Increasing the number of maximum loops did eventually lead to a
successful return from the function, but would later fail the actual
self test.

3 files changed, 13 insertions, 5 deletions

diff --git a/Kernel/Devices/HID/HIDManagement.cpp b/Kernel/Devices/HID/HIDManagement.cpp
index 873e5f8070..1d45324d0e 100644
--- a/Kernel/Devices/HID/HIDManagement.cpp
+++ b/Kernel/Devices/HID/HIDManagement.cpp
@@ -107,12 +107,20 @@ UNMAP_AFTER_INIT ErrorOr<void> HIDManagement::enumerate()
     // set to emulate PS/2, we should not initialize the PS/2 controller.
     if (kernel_command_line().disable_ps2_controller())
         return {};
-    if (ACPI::Parser::the() && !ACPI::Parser::the()->have_8042())
-        return {};
     m_i8042_controller = I8042Controller::initialize();
 
+    // Note: If ACPI is disabled or doesn't indicate that we have an i8042, we
+    // still perform a manual existence check via probing, which is relevant on
+    // QEMU, for example. This probing check is known to not work on bare metal
+    // in all cases, so if we can get a 'yes' from ACPI, we skip it.
+    auto has_i8042_controller = false;
+    if (ACPI::Parser::the() && ACPI::Parser::the()->have_8042())
+        has_i8042_controller = true;
+    else if (m_i8042_controller->check_existence_via_probing({}))
+        has_i8042_controller = true;
+
     // Note: If we happen to not have i8042 just return "gracefully" for now.
-    if (!m_i8042_controller->check_existence({}))
+    if (!has_i8042_controller)
         return {};
     TRY(m_i8042_controller->detect_devices());
     if (m_i8042_controller->mouse())
diff --git a/Kernel/Devices/HID/I8042Controller.cpp b/Kernel/Devices/HID/I8042Controller.cpp
index a302449be0..a970d0312d 100644
--- a/Kernel/Devices/HID/I8042Controller.cpp
+++ b/Kernel/Devices/HID/I8042Controller.cpp
@@ -31,7 +31,7 @@ UNMAP_AFTER_INIT I8042Controller::I8042Controller()
 {
 }
 
-UNMAP_AFTER_INIT bool I8042Controller::check_existence(Badge<HIDManagement>)
+UNMAP_AFTER_INIT bool I8042Controller::check_existence_via_probing(Badge<HIDManagement>)
 {
     {
         SpinlockLocker lock(m_lock);
diff --git a/Kernel/Devices/HID/I8042Controller.h b/Kernel/Devices/HID/I8042Controller.h
index 98b85a9e85..f6d250b7b1 100644
--- a/Kernel/Devices/HID/I8042Controller.h
+++ b/Kernel/Devices/HID/I8042Controller.h
@@ -143,7 +143,7 @@ public:
     RefPtr<KeyboardDevice> keyboard() const;
 
     // Note: This function exists only for the initialization process of the controller
-    bool check_existence(Badge<HIDManagement>);
+    bool check_existence_via_probing(Badge<HIDManagement>);
 
 private:
     I8042Controller();