[PATCH v2 1/2] Input: xpad - query MS OS descriptor for BTP-KP20D

[PATCH v2 1/2] Input: xpad - query MS OS descriptor for BTP-KP20D

[Aaron Ma]

The Beitong BTP-KP20D dongle cycles through its operating modes and
never becomes usable unless the host requests the Microsoft OS string
descriptor at index 0xee. Windows makes this request while discovering
the XUSB10 compatible ID, but Linux USB core does not query Microsoft
OS descriptors.

Add a device-specific quirk that performs the request during probe,
allowing the dongle to remain in Xbox 360 mode.

Signed-off-by: Aaron Ma <mapengyu@gmail.com>
---
 drivers/input/joystick/xpad.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/input/joystick/xpad.c b/drivers/input/joystick/xpad.c
index feb8f368f834e..1616047e65f5e 100644
--- a/drivers/input/joystick/xpad.c
+++ b/drivers/input/joystick/xpad.c
@@ -72,6 +72,7 @@
 #define PKT_XBE2_FW_5_11    4
 
 #define FLAG_DELAY_INIT BIT(0)
+#define FLAG_MS_OS_DESC BIT(1)
 
 static bool dpad_to_buttons;
 module_param(dpad_to_buttons, bool, S_IRUGO);
@@ -334,6 +335,7 @@ static const struct xpad_device {
 	{ 0x1ee9, 0x1590, "ZOTAC Gaming Zone", 0, XTYPE_XBOX360 },
 	{ 0x20bc, 0x5134, "BETOP BTP-KP50B Xinput Dongle", 0, XTYPE_XBOX360 },
 	{ 0x20bc, 0x514a, "BETOP BTP-KP50C Xinput Dongle", 0, XTYPE_XBOX360 },
+	{ 0x20bc, 0x5159, "Beitong BTP-KP20D Controller", 0, XTYPE_XBOX360, FLAG_MS_OS_DESC },
 	{ 0x20d6, 0x2001, "BDA Xbox Series X Wired Controller", 0, XTYPE_XBOXONE },
 	{ 0x20d6, 0x2009, "PowerA Enhanced Wired Controller for Xbox Series X|S", 0, XTYPE_XBOXONE },
 	{ 0x20d6, 0x2064, "PowerA Wired Controller for Xbox", MAP_SHARE_BUTTON, XTYPE_XBOXONE },
@@ -786,6 +788,24 @@ static int xpad_start_input(struct usb_xpad *xpad);
 static void xpadone_ack_mode_report(struct usb_xpad *xpad, u8 seq_num);
 static void xpad360w_poweroff_controller(struct usb_xpad *xpad);
 
+static void xpad_query_ms_os_descriptor(struct usb_device *udev)
+{
+	u8 *descriptor;
+	int error;
+
+	descriptor = kmalloc(18, GFP_KERNEL);
+	if (!descriptor)
+		return;
+
+	error = usb_get_descriptor(udev, USB_DT_STRING, 0xee,
+				   descriptor, 18);
+	if (error != 18)
+		dev_warn(&udev->dev,
+			 "unable to query MS OS descriptor: %d\n", error);
+
+	kfree(descriptor);
+}
+
 /*
  *	xpad_process_packet
  *
@@ -2055,6 +2075,9 @@ static int xpad_probe(struct usb_interface *intf, const struct usb_device_id *id
 			break;
 	}
 
+	if (xpad_device[i].flags & FLAG_MS_OS_DESC)
+		xpad_query_ms_os_descriptor(udev);
+
 	xpad = kzalloc_obj(*xpad);
 	if (!xpad)
 		return -ENOMEM;
-- 
2.53.0

[PATCH v2 2/2] Input: xpad - add wired Beitong BTP-KP20D support

[Aaron Ma]

The wired BTP-KP20D resets itself when its interrupt-IN pipe is idle
for a few seconds, causing periodic re-enumeration whenever no
userspace client holds the input device open. Add a FLAG_KEEPALIVE
quirk that keeps the input URB running from probe to disconnect,
mirroring the XTYPE_XBOX360W URB lifecycle.

The device also needs the MS OS descriptor query to stay in Xbox 360
mode.

Stop any active output URB on probe failure before freeing its URB and
DMA buffer. LED setup may submit the output URB before input
initialization completes.

Signed-off-by: Aaron Ma <mapengyu@gmail.com>
---
Changes in v2:
- Stop the output URB before freeing it on probe failure.

 drivers/input/joystick/xpad.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/input/joystick/xpad.c b/drivers/input/joystick/xpad.c
index 1616047e65f5e..9adc419066353 100644
--- a/drivers/input/joystick/xpad.c
+++ b/drivers/input/joystick/xpad.c
@@ -73,6 +73,7 @@
 
 #define FLAG_DELAY_INIT BIT(0)
 #define FLAG_MS_OS_DESC BIT(1)
+#define FLAG_KEEPALIVE  BIT(2)
 
 static bool dpad_to_buttons;
 module_param(dpad_to_buttons, bool, S_IRUGO);
@@ -335,6 +336,7 @@ static const struct xpad_device {
 	{ 0x1ee9, 0x1590, "ZOTAC Gaming Zone", 0, XTYPE_XBOX360 },
 	{ 0x20bc, 0x5134, "BETOP BTP-KP50B Xinput Dongle", 0, XTYPE_XBOX360 },
 	{ 0x20bc, 0x514a, "BETOP BTP-KP50C Xinput Dongle", 0, XTYPE_XBOX360 },
+	{ 0x20bc, 0x5158, "Beitong BTP-KP20D Controller", 0, XTYPE_XBOX360, FLAG_MS_OS_DESC | FLAG_KEEPALIVE },
 	{ 0x20bc, 0x5159, "Beitong BTP-KP20D Controller", 0, XTYPE_XBOX360, FLAG_MS_OS_DESC },
 	{ 0x20d6, 0x2001, "BDA Xbox Series X Wired Controller", 0, XTYPE_XBOXONE },
 	{ 0x20d6, 0x2009, "PowerA Enhanced Wired Controller for Xbox Series X|S", 0, XTYPE_XBOXONE },
@@ -780,6 +782,7 @@ struct usb_xpad {
 	time64_t mode_btn_down_ts;
 	bool delay_init;		/* init packets should be delayed */
 	bool delayed_init_done;
+	bool keepalive;			/* int URB must run from probe to disconnect */
 };
 
 static int xpad_init_input(struct usb_xpad *xpad);
@@ -1971,7 +1974,7 @@ static int xpad_init_input(struct usb_xpad *xpad)
 
 	input_set_drvdata(input_dev, xpad);
 
-	if (xpad->xtype != XTYPE_XBOX360W) {
+	if (xpad->xtype != XTYPE_XBOX360W && !xpad->keepalive) {
 		input_dev->open = xpad_open;
 		input_dev->close = xpad_close;
 	}
@@ -2105,6 +2108,8 @@ static int xpad_probe(struct usb_interface *intf, const struct usb_device_id *id
 	xpad->name = xpad_device[i].name;
 	if (xpad_device[i].flags & FLAG_DELAY_INIT)
 		xpad->delay_init = true;
+	if (xpad_device[i].flags & FLAG_KEEPALIVE)
+		xpad->keepalive = true;
 
 	xpad->packet_type = PKT_XB;
 	INIT_WORK(&xpad->work, xpad_presence_work);
@@ -2227,10 +2232,24 @@ static int xpad_probe(struct usb_interface *intf, const struct usb_device_id *id
 		error = xpad_init_input(xpad);
 		if (error)
 			goto err_deinit_output;
+
+		if (xpad->keepalive) {
+			/*
+			 * The device resets itself when the interrupt-IN pipe
+			 * is idle for a few seconds, so keep the URB running
+			 * from probe until disconnect.
+			 */
+			error = xpad_start_input(xpad);
+			if (error)
+				goto err_deinit_input;
+		}
 	}
 	return 0;
 
+err_deinit_input:
+	xpad_deinit_input(xpad);
 err_deinit_output:
+	xpad_stop_output(xpad);
 	xpad_deinit_output(xpad);
 err_free_in_urb:
 	usb_free_urb(xpad->irq_in);
@@ -2247,6 +2266,8 @@ static void xpad_disconnect(struct usb_interface *intf)
 
 	if (xpad->xtype == XTYPE_XBOX360W)
 		xpad360w_stop_input(xpad);
+	else if (xpad->keepalive)
+		xpad_stop_input(xpad);
 
 	xpad_deinit_input(xpad);
 
@@ -2288,6 +2309,8 @@ static int xpad_suspend(struct usb_interface *intf, pm_message_t message)
 		 */
 		if (auto_poweroff && xpad->pad_present)
 			xpad360w_poweroff_controller(xpad);
+	} else if (xpad->keepalive) {
+		xpad_stop_input(xpad);
 	} else {
 		guard(mutex)(&input->mutex);
 
@@ -2309,6 +2332,9 @@ static int xpad_resume(struct usb_interface *intf)
 	if (xpad->xtype == XTYPE_XBOX360W)
 		return xpad360w_start_input(xpad);
 
+	if (xpad->keepalive)
+		return xpad_start_input(xpad);
+
 	guard(mutex)(&input->mutex);
 
 	if (input_device_enabled(input))
-- 
2.53.0

Re: [PATCH v2 1/2] Input: xpad - query MS OS descriptor for BTP-KP20D

[Shengyu Qu]

[-- Attachment #1.1: Type: text/plain, Size: 798 bytes --]



在 2026/8/1 15:56, Aaron Ma 写道:

> @@ -334,6 +335,7 @@ static const struct xpad_device {
>   	{ 0x1ee9, 0x1590, "ZOTAC Gaming Zone", 0, XTYPE_XBOX360 },
>   	{ 0x20bc, 0x5134, "BETOP BTP-KP50B Xinput Dongle", 0, XTYPE_XBOX360 },
>   	{ 0x20bc, 0x514a, "BETOP BTP-KP50C Xinput Dongle", 0, XTYPE_XBOX360 },
> +	{ 0x20bc, 0x5159, "Beitong BTP-KP20D Controller", 0, XTYPE_XBOX360, FLAG_MS_OS_DESC },

I think using dongle instead of controller is more clear? Since
controller itself use a different VID.

>   	{ 0x20d6, 0x2001, "BDA Xbox Series X Wired Controller", 0, XTYPE_XBOXONE },
>   	{ 0x20d6, 0x2009, "PowerA Enhanced Wired Controller for Xbox Series X|S", 0, XTYPE_XBOXONE },
>   	{ 0x20d6, 0x2064, "PowerA Wired Controller for Xbox", MAP_SHARE_BUTTON, XTYPE_XBOXONE },

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [PATCH v2 1/2] Input: xpad - query MS OS descriptor for BTP-KP20D

[Pengyu Ma]

On Mon, Aug 3, 2026 at 5:40 PM Shengyu Qu <wiagn233@outlook.com> wrote:
>
>
>
> 在 2026/8/1 15:56, Aaron Ma 写道:
>
> > @@ -334,6 +335,7 @@ static const struct xpad_device {
> >       { 0x1ee9, 0x1590, "ZOTAC Gaming Zone", 0, XTYPE_XBOX360 },
> >       { 0x20bc, 0x5134, "BETOP BTP-KP50B Xinput Dongle", 0, XTYPE_XBOX360 },
> >       { 0x20bc, 0x514a, "BETOP BTP-KP50C Xinput Dongle", 0, XTYPE_XBOX360 },
> > +     { 0x20bc, 0x5159, "Beitong BTP-KP20D Controller", 0, XTYPE_XBOX360, FLAG_MS_OS_DESC },
>
> I think using dongle instead of controller is more clear? Since
> controller itself use a different VID.
>

This is the controller VID.
The controller is idVendor=20bc
The dongle ID is idVendor=20dd.

Aaron

> >       { 0x20d6, 0x2001, "BDA Xbox Series X Wired Controller", 0, XTYPE_XBOXONE },
> >       { 0x20d6, 0x2009, "PowerA Enhanced Wired Controller for Xbox Series X|S", 0, XTYPE_XBOXONE },
> >       { 0x20d6, 0x2064, "PowerA Wired Controller for Xbox", MAP_SHARE_BUTTON, XTYPE_XBOXONE },

Re: [PATCH v2 1/2] Input: xpad - query MS OS descriptor for BTP-KP20D

[Shengyu Qu]

[-- Attachment #1.1: Type: text/plain, Size: 926 bytes --]


在 2026/8/3 20:13, Pengyu Ma 写道:
> On Mon, Aug 3, 2026 at 5:40 PM Shengyu Qu <wiagn233@outlook.com> wrote:
>>
>>
>>
>> 在 2026/8/1 15:56, Aaron Ma 写道:
>>
>>> @@ -334,6 +335,7 @@ static const struct xpad_device {
>>>        { 0x1ee9, 0x1590, "ZOTAC Gaming Zone", 0, XTYPE_XBOX360 },
>>>        { 0x20bc, 0x5134, "BETOP BTP-KP50B Xinput Dongle", 0, XTYPE_XBOX360 },
>>>        { 0x20bc, 0x514a, "BETOP BTP-KP50C Xinput Dongle", 0, XTYPE_XBOX360 },
>>> +     { 0x20bc, 0x5159, "Beitong BTP-KP20D Controller", 0, XTYPE_XBOX360, FLAG_MS_OS_DESC },
>>
>> I think using dongle instead of controller is more clear? Since
>> controller itself use a different VID.
>>
> 
> This is the controller VID.
> The controller is idVendor=20bc
> The dongle ID is idVendor=20dd.
> 
> Aaron

It's not consistent with your patch description. Also interestingly, 
this seems not working on KP50B/C.

Shengyu

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [PATCH v2 1/2] Input: xpad - query MS OS descriptor for BTP-KP20D

[Pengyu Ma]

On Tue, Aug 4, 2026 at 1:32 AM Shengyu Qu <wiagn233@outlook.com> wrote:
>
>
> 在 2026/8/3 20:13, Pengyu Ma 写道:
> > On Mon, Aug 3, 2026 at 5:40 PM Shengyu Qu <wiagn233@outlook.com> wrote:
> >>
> >>
> >>
> >> 在 2026/8/1 15:56, Aaron Ma 写道:
> >>
> >>> @@ -334,6 +335,7 @@ static const struct xpad_device {
> >>>        { 0x1ee9, 0x1590, "ZOTAC Gaming Zone", 0, XTYPE_XBOX360 },
> >>>        { 0x20bc, 0x5134, "BETOP BTP-KP50B Xinput Dongle", 0, XTYPE_XBOX360 },
> >>>        { 0x20bc, 0x514a, "BETOP BTP-KP50C Xinput Dongle", 0, XTYPE_XBOX360 },
> >>> +     { 0x20bc, 0x5159, "Beitong BTP-KP20D Controller", 0, XTYPE_XBOX360, FLAG_MS_OS_DESC },
> >>
> >> I think using dongle instead of controller is more clear? Since
> >> controller itself use a different VID.
> >>
> >
> > This is the controller VID.
> > The controller is idVendor=20bc
> > The dongle ID is idVendor=20dd.
> >
> > Aaron
>
> It's not consistent with your patch description. Also interestingly,
> this seems not working on KP50B/C.

Please provide KP50B/C IDs.
How did you tested?
Could you attach the dmesg?

Aaron

>
> Shengyu