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fix(gamepad/windows): Steam-accepted Deck unit serial un-mangles the controller name

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Steam validates the Deck unit serial's format before accepting it. Our
"PFDK..." serial was REJECTED ("Invalid or missing unit serial number"), so
Steam substituted a hash identity and mangled the displayed name to
"Steam Deck Controllerggg" on every host tested. An 'F'-leading serial passes,
so switch to "FVPF..." — keeps the PunktFunk marker one slot in, still distinct
from a real Deck's "FVZZ..." for the Linux self-detection in
physical_steam_controller_present(). The name now shows a clean "Steam Deck
Controller" with a serial-derived handle (verified on .173).

Also fix the UMDF driver's 0xAE GET_STRING_ATTRIBUTE handler to echo the
requested attribute id faithfully instead of collapsing board-serial (0x00)
requests to unit-serial (0x01). Steam still logs a benign "Deck Controller PCB
Serial# invalid" for the board serial — it validates that against a
Valve-internal format for ANY value, including an empty one (verified) — but
that line does not mangle the name, change the handle, or block promotion.

Applied to both transports: host inject/proto/steam_proto.rs::deck_serial
(Linux gadget/usbip) and the pf-dualsense UMDF driver (Windows), which mirror
each other's serial format.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
Enrico Bühler
2026-07-14 14:21:19 +02:00
parent d8e8529cd7
commit f3b6ccaa7f
3 changed files with 43 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files
crates/punktfunk-host/src/inject/proto/steam_proto.rs
+10 -6
View File
@@ -542,12 +542,16 @@ pub fn deck_unit_id(index: u8) -> u32 {
0x5046_0000 | index as u32 0x5046_0000 | index as u32
} }
/// A Steam-accepted alphanumeric unit serial (a real Deck's is e.g. `"FVZZ4200469B"`; Steam rejects /// A Steam-accepted alphanumeric unit serial (a real Deck's is e.g. `"FVZZ4200469B"`). Steam
/// a too-short/oddly-formatted one as "Invalid or missing unit serial number" and substitutes its /// validates the serial's FORMAT before accepting it: a `"PF"`-leading serial is REJECTED
/// own — benign, but we present a clean 12-char one). Derived from [`deck_unit_id`] so the `0xAE` /// ("Invalid or missing unit serial number …") and Steam then substitutes a hash AND mangles the
/// serial reply and the `0x83` unit-id attrs stay consistent. /// displayed controller name (observed as "Steam Deck Controllerggg" on Windows). An `'F'`-leading
/// serial passes, so we keep the PunktFunk marker one slot in (`"FVPF"`) — still distinct from a
/// real Deck's `"FVZZ"` for the self-detection below while satisfying Steam's format check.
/// Derived from [`deck_unit_id`] so the `0xAE` serial reply and the `0x83` unit-id attrs stay
/// consistent. (The Windows UMDF driver mirrors this exact format — see pf-dualsense lib.rs.)
pub fn deck_serial(index: u8) -> String { pub fn deck_serial(index: u8) -> String {
format!("PFDK{:08X}", deck_unit_id(index)) format!("FVPF{:08X}", deck_unit_id(index))
} }
/// The neutral 64-byte Deck input report (header only, all controls released) — the report the /// The neutral 64-byte Deck input report (header only, all controls released) — the report the
@@ -914,7 +918,7 @@ mod tests {
fn deck_feature_reply_contract() { fn deck_feature_reply_contract() {
let serial = deck_serial(0); let serial = deck_serial(0);
let unit_id = deck_unit_id(0); let unit_id = deck_unit_id(0);
assert_eq!(serial, "PFDK50460000"); // 12-char alphanumeric, derived from the unit id assert_eq!(serial, "FVPF50460000"); // 12-char alphanumeric, derived from the unit id
assert_eq!(serial.len(), 12); assert_eq!(serial.len(), 12);
// 0x83 GET_ATTRIBUTES_VALUES: header + (0x0a, unit_id) at the 3rd attribute slot. // 0x83 GET_ATTRIBUTES_VALUES: header + (0x0a, unit_id) at the 3rd attribute slot.
crates/punktfunk-host/src/punktfunk1.rs
+2 -2
View File
@@ -2865,7 +2865,7 @@ fn degrade_if_no_uhid(chosen: GamepadPref) -> GamepadPref {
/// device (vhci resolves through `vhci_hcd`, NOT `/devices/virtual/`), so a just-ended session's /// device (vhci resolves through `vhci_hcd`, NOT `/devices/virtual/`), so a just-ended session's
/// pad still detaching — or a concurrent session's live one — read as "physical" and degraded /// pad still detaching — or a concurrent session's live one — read as "physical" and degraded
/// every back-to-back Deck session to DualSense (observed live on Bazzite 2026-07-04). Ours are /// every back-to-back Deck session to DualSense (observed live on Bazzite 2026-07-04). Ours are
/// recognizable by the `PFDK…` serial ([`steam_proto::deck_serial`]) in `HID_UNIQ`, with the /// recognizable by the `FVPF…` serial ([`steam_proto::deck_serial`]) in `HID_UNIQ`, with the
/// vhci path as belt and braces. /// vhci path as belt and braces.
#[cfg(target_os = "linux")] #[cfg(target_os = "linux")]
fn physical_steam_controller_present() -> bool { fn physical_steam_controller_present() -> bool {
@@ -2877,7 +2877,7 @@ fn physical_steam_controller_present() -> bool {
return false; return false;
} }
if std::fs::read_to_string(e.path().join("uevent")) if std::fs::read_to_string(e.path().join("uevent"))
.is_ok_and(|u| u.lines().any(|l| l.starts_with("HID_UNIQ=PFDK"))) .is_ok_and(|u| u.lines().any(|l| l.starts_with("HID_UNIQ=FVPF")))
{ {
return false; // one of our own virtual Decks return false; // one of our own virtual Decks
} }
packaging/windows/drivers/pf-dualsense/src/lib.rs
+31 -14
View File
@@ -673,21 +673,31 @@ fn deck_feature_reply() -> [u8; 64] {
.unwrap_or(0) .unwrap_or(0)
& 0xFF; & 0xFF;
let unit_id: u32 = 0x5046_0000 | idx; let unit_id: u32 = 0x5046_0000 | idx;
let serial = format!("PFDK{unit_id:08X}"); // Steam validates the unit serial's PREFIX before accepting it: a "PF"-leading serial is
let serial = serial.as_bytes(); // REJECTED ("Invalid or missing unit serial number …") and Steam then substitutes a hash and
// MANGLES the displayed name ("Steam Deck Controllerggg"). An 'F'-leading serial passes, so we
// keep our PunktFunk marker one slot in ("FVPF") — still distinct enough for the Linux side's
// physical-Deck self-detection while satisfying Steam's format check. (This, not the build-time
// attributes below, is what un-mangles the name — verified by A/B on .173.)
let unit_serial = format!("FVPF{unit_id:08X}");
let unit_serial = unit_serial.as_bytes();
let mut r = [0u8; 64]; let mut r = [0u8; 64];
match last[0] { match last[0] {
0x83 => { 0x83 => {
// GET_ATTRIBUTES_VALUES: [0x83, 0x2d, then 9x (attr-id, value u32-LE)]. // GET_ATTRIBUTES_VALUES: [0x83, 0x2d, then 9x (attr-id, value u32-LE)].
r[0] = 0x83; r[0] = 0x83;
r[1] = 0x2D; r[1] = 0x2D;
// Attribute semantics per SDL's controller_constants.h: 0x04 = FIRMWARE_BUILD_TIME
// and 0x0A = BOOTLOADER_BUILD_TIME are unix timestamps that must look like real build
// dates (the old unit-id-derived junk here was cosmetic; the name mangling was the
// serial prefix). Uniqueness rides the serial.
let attrs: [(u8, u32); 9] = [ let attrs: [(u8, u32); 9] = [
(0x01, 0x1205), (0x01, 0x1205), // ATTRIB_PRODUCT_ID
(0x02, 0), (0x02, 0), // ATTRIB_CAPABILITIES
(0x0A, unit_id), (0x0A, 0x6408_9000), // ATTRIB_BOOTLOADER_BUILD_TIME (2023-03-08)
(0x04, unit_id ^ 0x5555_5555), (0x04, 0x66A8_C000), // ATTRIB_FIRMWARE_BUILD_TIME (2024-07-30)
(0x09, 0x2E), (0x09, 0x2E), // ATTRIB_BOARD_REVISION (captured)
(0x0B, 0x0FA0), (0x0B, 0x0FA0), // ATTRIB_CONNECTION_INTERVAL_IN_US (4 ms)
(0x0D, 0), (0x0D, 0),
(0x0C, 0), (0x0C, 0),
(0x0E, 0), (0x0E, 0),
@@ -700,12 +710,19 @@ fn deck_feature_reply() -> [u8; 64] {
} }
} }
0xAE => { 0xAE => {
// GET_STRING_ATTRIBUTE: [0xAE, len, attr, ascii…]. // GET_STRING_ATTRIBUTE: [0xAE, len, attr, ascii…]. Steam requests two strings: attr
let attr = if last[2] != 0 { last[2] } else { 0x01 }; // 0x00 = ATTRIB_STR_BOARD_SERIAL (the PCB serial) and 0x01 = ATTRIB_STR_UNIT_SERIAL.
// Echo the exact attr requested (last[2]) — the unit serial is the one that matters:
// getting its format right (FVPF…, see above) is what un-mangles the displayed name.
// Steam ALSO validates the PCB serial against a Valve-internal format we don't have a
// real capture of; it logs "Deck Controller PCB Serial# invalid" for ANY value we send
// (including an empty one — verified on .173), but that line is BENIGN: unlike a bad
// unit serial, it does not mangle the name, change the handle, or block promotion. So we
// serve the unit serial for both attrs and accept the log.
r[0] = 0xAE; r[0] = 0xAE;
r[1] = serial.len() as u8; r[1] = unit_serial.len() as u8;
r[2] = attr; r[2] = last[2];
r[3..3 + serial.len()].copy_from_slice(serial); r[3..3 + unit_serial.len()].copy_from_slice(unit_serial);
} }
_ => r.copy_from_slice(&last), _ => r.copy_from_slice(&last),
} }
@@ -779,7 +796,7 @@ fn on_get_string(request: &Request) -> NTSTATUS {
.map(|v| v.read_u32(OFF_PAD_INDEX)) .map(|v| v.read_u32(OFF_PAD_INDEX))
.unwrap_or(0) .unwrap_or(0)
& 0xFF; & 0xFF;
format!("PFDK{:08X}", 0x5046_0000u32 | idx) format!("FVPF{:08X}", 0x5046_0000u32 | idx)
} }
_ => "35533AD6E774".into(), _ => "35533AD6E774".into(),
}, },