[vk_texture_cache] drop depth comparison sampler fallback (#4408)

- [x] I have read and followed the [Contribution Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/CONTRIBUTING.md#code-contributions).
- [x] I have read and followed the [AI Policy](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/AI.md)
- [x] I have read and followed the [Coding Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/Coding.md) to the best of my ability.

-------------------

This fixes the flashlight in Alan Wake.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4408
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>

src/common/CMakeLists.txt

@@ -110,6 +110,7 @@ add_library(
     socket_types.h
     sparse_large_vector.cpp
     sparse_large_vector.h
+    spin_lock.h
     stb.cpp
     stb.h
     steady_clock.cpp

src/common/spin_lock.h

@@ -0,0 +1,50 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+// SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#ifdef _MSC_VER
+#include <intrin.h>
+#elif defined(ARCHITECTURE_x86_64)
+#include <xmmintrin.h>
+#endif
+#include <atomic>
+
+namespace Common {
+
+/// @brief A lock similar to mutex that forces a thread to spin wait instead calling the
+/// supervisor. Should be used on short sequences of code.
+struct SpinLock {
+    SpinLock() noexcept = default;
+    SpinLock(const SpinLock&) noexcept = delete;
+    SpinLock& operator=(const SpinLock&) noexcept = delete;
+    SpinLock(SpinLock&&) noexcept = delete;
+    SpinLock& operator=(SpinLock&&) noexcept = delete;
+
+    inline void lock() noexcept {
+        while (lck.test_and_set(std::memory_order_acquire)) {
+#if defined(ARCHITECTURE_x86_64)
+            _mm_pause();
+#elif defined(ARCHITECTURE_arm64) && defined(_MSC_VER)
+            __yield();
+#elif defined(ARCHITECTURE_arm64)
+            asm("yield");
+#endif
+        }
+    }
+
+    inline void unlock() noexcept {
+        lck.clear(std::memory_order_release);
+    }
+
+    [[nodiscard]] inline bool try_lock() noexcept {
+        return !lck.test_and_set(std::memory_order_acquire);
+    }
+
+    std::atomic_flag lck = ATOMIC_FLAG_INIT;
+};
+
+} // namespace Common

src/core/frontend/applets/controller.cpp

@@ -12,6 +12,7 @@
 #include "hid_core/frontend/emulated_controller.h"
 #include "hid_core/hid_core.h"
 #include "hid_core/hid_types.h"
+#include <array>
 
 namespace Core::Frontend {
 
@@ -29,23 +30,39 @@ void DefaultControllerApplet::ReconfigureControllers(ReconfigureCallback callbac
 
     const std::size_t min_supported_players =
         parameters.enable_single_mode ? 1 : parameters.min_players;
+    using Core::HID::NpadStyleIndex;
+    const std::size_t max_supported_players = parameters.enable_single_mode ? 1 : parameters.max_players;
+    std::size_t num_selected_players = 0;
+    std::array<bool, HID::HIDCore::available_controllers> keep_connected{};
 
-    // Disconnect Handheld first.
+    // reserve existing AND valid players before filling slots. include Handheld, but not other
+    for (std::size_t index = 0; index < hid_core.available_controllers - 1; ++index) {
+        const auto* controller = hid_core.GetEmulatedControllerByIndex(index);
+        if (!parameters.keep_controllers_connected || !controller->IsConnected() || num_selected_players >= max_supported_players) continue;
+
+        const auto style = controller->GetNpadStyleIndex();
+        keep_connected[index] =
+            (style == NpadStyleIndex::Fullkey && parameters.allow_pro_controller) ||
+            (style == NpadStyleIndex::JoyconDual && parameters.allow_dual_joycons) ||
+            (style == NpadStyleIndex::JoyconLeft && parameters.allow_left_joycon) ||
+            (style == NpadStyleIndex::JoyconRight && parameters.allow_right_joycon) ||
+            (style == NpadStyleIndex::Handheld && parameters.enable_single_mode && parameters.allow_handheld && !Settings::IsDockedMode()) ||
+            (style == NpadStyleIndex::GameCube && parameters.allow_gamecube_controller);
+        num_selected_players += keep_connected[index];
+    }
     auto* handheld = hid_core.GetEmulatedController(Core::HID::NpadIdType::Handheld);
-    handheld->Disconnect();
+    if (!keep_connected[hid_core.available_controllers - 2]) handheld->Disconnect();
 
     // Deduce the best configuration based on the input parameters.
     for (std::size_t index = 0; index < hid_core.available_controllers - 2; ++index) {
         auto* controller = hid_core.GetEmulatedControllerByIndex(index);
 
-        // First, disconnect all controllers regardless of the value of keep_controllers_connected.
-        // This makes it easy to connect the desired controllers.
+        if (keep_connected[index]) continue;
         controller->Disconnect();
 
-        // Only connect the minimum number of required players.
-        if (index >= min_supported_players) {
-            continue;
-        }
+        // only add players still needed to reach the minimum
+        if (num_selected_players >= min_supported_players) continue;
+        ++num_selected_players;
 
         // Connect controllers based on the following priority list from highest to lowest priority:
         // Pro Controller -> Dual Joycons -> Left Joycon/Right Joycon -> Handheld

src/core/hle/kernel/k_slab_heap.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
@@ -12,6 +12,7 @@
 #include "common/atomic_ops.h"
 #include "common/common_funcs.h"
 #include "common/common_types.h"
+#include "common/spin_lock.h"
 
 namespace Kernel {
 
@@ -29,7 +30,7 @@ public:
     };
 
 public:
-    KSlabHeapImpl() = default;
+    constexpr KSlabHeapImpl() = default;
 
     void Initialize() {
         ASSERT(m_head == nullptr);
@@ -67,7 +68,7 @@ public:
 
 private:
     std::atomic<Node*> m_head{};
-    std::mutex m_lock;
+    Common::SpinLock m_lock;
 };
 
 } // namespace impl

src/core/hle/kernel/k_thread.h

@@ -19,6 +19,7 @@
 
 #include "common/intrusive_red_black_tree.h"
 #include "common/scratch_buffer.h"
+#include "common/spin_lock.h"
 #include "core/arm/arm_interface.h"
 #include "core/hle/kernel/k_affinity_mask.h"
 #include "core/hle/kernel/k_light_lock.h"
@@ -919,7 +920,7 @@ private:
     bool m_resource_limit_release_hint{};
     bool m_is_kernel_address_key{};
     StackParameters m_stack_parameters{};
-    std::mutex m_context_guard{};
+    Common::SpinLock m_context_guard{};
 
     // For emulation
     std::shared_ptr<Common::Fiber> m_host_context{};

src/video_core/renderer_vulkan/vk_texture_cache.cpp

@@ -2850,8 +2850,6 @@ Sampler::VariantKey Sampler::MakeKey(const ImageView& image_view, bool is_depth)
     VariantKey key{};
     key.reduce_anisotropy = has_added_anisotropy && !image_view.SupportsAnisotropy();
     key.force_nearest = has_linear_filtering && IsPixelFormatInteger(image_view.format);
-    key.drop_depth_comparison =
-        is_depth && has_depth_comparison && !image_view.SupportsDepthComparison();
     key.drop_reduction = has_minmax_reduction && !image_view.SupportsMinmaxFilter();
     key.drop_custom_border = has_custom_border_colors && image_view.RequiresBorderColorFormat();
     key.srgb_border = has_srgb_border_color && IsPixelFormatSRGB(image_view.format);
@@ -2929,9 +2927,6 @@ VkSampler Sampler::Emplace(VariantKey key) {
         create_info.anisotropyEnable = static_cast<VkBool32>(default_anisotropy > 1.0f);
         create_info.maxAnisotropy = default_anisotropy;
     }
-    if (key.drop_depth_comparison) {
-        create_info.compareEnable = VK_FALSE;
-    }
     if (!custom_border) {
         create_info.borderColor = ConvertBorderColor(color);
     }

src/video_core/renderer_vulkan/vk_texture_cache.h

@@ -536,7 +536,6 @@ private:
     struct VariantKey {
         bool reduce_anisotropy;
         bool force_nearest;
-        bool drop_depth_comparison;
         bool drop_reduction;
         bool drop_custom_border;
         bool srgb_border;