fix/sdl3-gamepad-bugs (#19)

Four SDL3 gamepad fixes, all affecting real users with Switch controllers.

**Crash on reconnect / broken motion** — `GetFeaturesFlag()` was calling `SDL_DestroyProperties()` on properties owned by SDL internally, causing a use-after-free. This breaks gyro after the first read and crashes on reconnect. Fix: just don't destroy them.

**Thread safety in `GetGamepads()`** — was locking the wrong objects and holding locks across `yield` boundaries, which is undefined behavior with `System.Threading.Lock`. Fix: snapshot IDs under `_lock`, iterate outside it.

**Rumble NPE on disconnect** — `UpdateRumble()` called `_gamepad.Rumble()` without a null check; throws if the controller disconnects mid-update. Fix: `_gamepad?.Rumble(...)`.

**Linux: HIDAPI conflicts with `hid_nintendo`** — when the `hid_nintendo` kernel module is loaded, it provides evdev nodes for both the gamepad and IMU that SDL3's evdev backend correctly combines. HIDAPI conflicts with it, breaking gyro and wireless hotplug. Fix: detect `/sys/module/hid_nintendo` at startup and disable HIDAPI for Switch controllers automatically. Overridable via `SDL_JOYSTICK_HIDAPI_SWITCH=1`.

Tested with an 8BitDo Ultimate Bluetooth Controller on Linux.

Co-authored-by: schuay <36006+schuay@users.noreply.github.com>
Reviewed-on: https://git.ryujinx.app/projects/Ryubing/pulls/19

src/Ryujinx.Input.SDL3/SDL3Gamepad.cs

@@ -151,7 +151,9 @@ namespace Ryujinx.Input.SDL3
                 result |= GamepadFeaturesFlag.Led;
             }
             SDL_UnlockProperties(propID);
-            SDL_DestroyProperties(propID);
+
+            // NOTE: Do not call SDL_DestroyProperties here. These properties are owned
+            // internally by SDL and are freed when SDL_CloseGamepad is called (in Dispose).
 
             return result;
         }

src/Ryujinx.Input.SDL3/SDL3GamepadDriver.cs

@@ -331,28 +331,18 @@ namespace Ryujinx.Input.SDL3
 
         public IEnumerable<IGamepad> GetGamepads()
         {
-            lock (_gamepadsIds)
+            string[] ids;
+            lock (_lock)
             {
-                foreach (var gamepad in _gamepadsIds)
-                {
-                    yield return GetGamepad(gamepad.Value);
-                }
+                ids = _gamepadsIds.Values
+                    .Concat(_joyConsIds.Values)
+                    .Concat(_linkedJoyConsIds.Values)
+                    .ToArray();
             }
 
-            lock (_joyConsIds)
+            foreach (string id in ids)
             {
-                foreach (var gamepad in _joyConsIds)
-                {
-                    yield return GetGamepad(gamepad.Value);
-                }
-            }
-            
-            lock (_linkedJoyConsIds)
-            {
-                foreach (var gamepad in _linkedJoyConsIds)
-                {
-                    yield return GetGamepad(gamepad.Value);
-                }
+                yield return GetGamepad(id);
             }
         }
     }

src/Ryujinx.Input/HLE/NpadController.cs

@@ -563,7 +563,7 @@ namespace Ryujinx.Input.HLE
                     float low = Math.Min(1f, (float)((rightVibrationValue.AmplitudeLow * 0.85 + rightVibrationValue.AmplitudeHigh * 0.15) * controllerConfig.Rumble.StrongRumble));
                     float high = Math.Min(1f, (float)((leftVibrationValue.AmplitudeLow * 0.15 + leftVibrationValue.AmplitudeHigh * 0.85) * controllerConfig.Rumble.WeakRumble));
 
-                    _gamepad.Rumble(low, high, uint.MaxValue);
+                    _gamepad?.Rumble(low, high, uint.MaxValue);
 
                     Logger.Debug?.Print(LogClass.Hid, $"Effect for {controllerConfig.PlayerIndex} " +
                         $"L.low.amp={leftVibrationValue.AmplitudeLow}, " +

src/Ryujinx.SDL3.Common/SDL3Driver.cs

@@ -61,6 +61,14 @@ namespace Ryujinx.SDL3.Common
                 SDL_SetHint(SDL_HINT_JOYSTICK_HIDAPI_JOY_CONS, "1");
                 SDL_SetHint(SDL_HINT_VIDEO_ALLOW_SCREENSAVER, "1");
 
+                // When hid_nintendo is loaded, it creates separate evdev devices for the gamepad
+                // and IMU which SDL3's evdev backend combines via UNIQ matching. Using HIDAPI
+                // instead conflicts with the kernel driver and breaks motion and hotplug.
+                if (OperatingSystem.IsLinux() && Directory.Exists("/sys/module/hid_nintendo"))
+                {
+                    SDL_SetHint(SDL_HINT_JOYSTICK_HIDAPI_SWITCH, "0");
+                }
+
                 // NOTE: As of SDL3 2.24.0, joycons are combined by default but the motion source only come from one of them.
                 // We disable this behavior for now.
                 SDL_SetHint(SDL_HINT_JOYSTICK_HIDAPI_COMBINE_JOY_CONS, "0");