fix(steam-deck): use native USB hidraw path on Linux

Author: ReenigneArcher

docs/platform-support.md

@@ -150,14 +150,15 @@ 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 uses the Bluetooth HID transport tag:
-this remains visible to HIDAPI while avoiding the USB-only `hid-steam` match
-that otherwise suppresses the virtual endpoint's reports when a direct HID
-client opens it. The Generic Desktop/Game Pad descriptor remains available as
-an evdev fallback. 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. 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.
 
 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

@@ -324,12 +324,6 @@ namespace lvh::detail {
         // virtual endpoint.
         return BUS_VIRTUAL;
       }
-      if (profile.gamepad_kind == GamepadProfileKind::steam_deck) {
-        // hid-steam matches the Deck's USB identity and suppresses its input
-        // while a hidraw client is open. BUS_VIRTUAL avoids that driver but is
-        // filtered out by hidapi, so use its other supported HID transport.
-        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_BLUETOOTH, result);
+    auto event = create_started_profile_uhid_gamepad(gamepad, 11, options, descriptors[1], BUS_USB, 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_BLUETOOTH);
+  EXPECT_EQ(lvh::detail::test::linux_gamepad_uhid_bus(lvh::GamepadProfileKind::steam_deck), BUS_USB);
   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);