fix(steam-deck): preserve native SDL ownership

Author: ReenigneArcher

docs/platform-support.md

@@ -150,15 +150,14 @@ provides it separately on the UHID event.
 
 Steam Deck retains Valve's native identity and emits the 64-byte Deck state
 packet periodically so SDL's direct HIDAPI path can initialize before the first
-client input arrives. Its UHID endpoint keeps Valve's USB transport identity so
-Linux `hid-steam` can expose the dedicated hidraw client expected by SDL. When
-that client opens, `hid-steam` hands the native report stream to userspace; the
-Generic Desktop/Game Pad descriptor remains available as an evdev fallback when
-no direct HID client owns it. The backend answers the unit-serial feature query
-used during Linux registration, accepts the desktop-mapping/settings commands
-used by SDL, and forwards native `0xEB` rumble requests through the portable
-output callback. Each submitted native packet carries an advancing sequence
-number.
+client input arrives. Linux exposes that endpoint as Bluetooth HID so SDL can
+own the native hidraw stream directly; advertising it as USB would make the
+kernel's `hid-steam` driver claim the virtual endpoint and substitute an evdev
+controller. The Generic Desktop/Game Pad descriptor remains available as an
+evdev fallback. The backend answers the unit-serial feature query, accepts the
+desktop-mapping/settings commands used by SDL, and forwards native `0xEB`
+rumble requests through the portable output callback. Each submitted native
+packet carries an advancing sequence number.
 
 The backend opens `/dev/uhid` in nonblocking mode, matching the original
 asynchronous gamepad registration path. Its event reader is active before

src/platform/linux/uhid_backend.cpp

@@ -324,6 +324,12 @@ namespace lvh::detail {
         // virtual endpoint.
         return BUS_VIRTUAL;
       }
+      if (profile.gamepad_kind == GamepadProfileKind::steam_deck) {
+        // hid-steam claims USB endpoints with Valve's Deck VID/PID and
+        // publishes its own evdev device. Use a HID transport SDL accepts but
+        // hid-steam does not match so SDL can own the native hidraw stream.
+        return BUS_BLUETOOTH;
+      }
       return to_uhid_bus(profile.bus_type);
     }
 

tests/fixtures/linux_backend_test_hooks.cpp

@@ -1695,7 +1695,7 @@ namespace lvh::detail::test {
     options.metadata.stable_id = "linux-steam-deck";
 
     UhidGamepad gamepad {descriptors[0]};
-    auto event = create_started_profile_uhid_gamepad(gamepad, 11, options, descriptors[1], BUS_USB, result);
+    auto event = create_started_profile_uhid_gamepad(gamepad, 11, options, descriptors[1], BUS_BLUETOOTH, result);
     gamepad.set_output_callback([&result](const GamepadOutput &output) {
       if (output.kind == GamepadOutputKind::rumble) {
         ++result.output.callback_count;

tests/unit/test_linux_backend.cpp

@@ -124,7 +124,7 @@ TEST_F(LinuxBackendTest, TranslatesMouseButtonsAndBusTypes) {
   EXPECT_EQ(lvh::detail::test::linux_uhid_bus(lvh::BusType::bluetooth), BUS_BLUETOOTH);
   EXPECT_EQ(lvh::detail::test::linux_gamepad_uhid_bus(lvh::GamepadProfileKind::xbox_series), BUS_USB);
   EXPECT_EQ(lvh::detail::test::linux_gamepad_uhid_bus(lvh::GamepadProfileKind::switch_pro), BUS_VIRTUAL);
-  EXPECT_EQ(lvh::detail::test::linux_gamepad_uhid_bus(lvh::GamepadProfileKind::steam_deck), BUS_USB);
+  EXPECT_EQ(lvh::detail::test::linux_gamepad_uhid_bus(lvh::GamepadProfileKind::steam_deck), BUS_BLUETOOTH);
   EXPECT_EQ(lvh::detail::test::linux_uinput_bus(lvh::BusType::bluetooth), BUS_BLUETOOTH);
 
   EXPECT_EQ(lvh::detail::test::linux_pen_tool(lvh::PenToolType::pen), BTN_TOOL_PEN);

tests/unit/test_windows_consumers.cpp

@@ -437,8 +437,10 @@ namespace {
           SDL_GetGamepadProductForID(gamepad_id) == product_id
         ) {
           auto *opened = SDL_OpenGamepad(gamepad_id);
-          SDL_free(gamepads);
-          return {opened, &SDL_CloseGamepad};
+          if (opened != nullptr) {
+            SDL_free(gamepads);
+            return {opened, &SDL_CloseGamepad};
+          }
         }
       }
       SDL_free(gamepads);