From: John Bauer <johnebgood@securitylive.com>

The OBSBOT series of cameras misreports the minimum relative
pan_speed, tilt_speed and zoom_continuous v4l2 controls resulting
in the inability to control the camera with finesse with an analog
stick or other programmatic methods. This patch applies to all
Remo (OBSBOT) vendor cameras with the vendor ID of 0x3564. If the
vendor fixes the firmware this behavior should still remain valid.
With this broad vendor fix when new devices are released the kernel
module won't need to be modified. When the vendor fixes the firmware the
device list can be modified with finer grained device filters.

Signed-off-by: John Bauer <johnebgood@securitylive.com>
---
If the Remo/OBSBOT vendor filter is considered too broad I will track down 
all of the current product ID's and update the device list. It's currently 
unknown if the vendor is pursuing a fix this issue; this issue has been 
reported and known to them for over a year. Their only support channel 
is their Facebook group. 
---
 drivers/media/usb/uvc/uvc_ctrl.c   | 27 ++++++++++++++++++++++++++-
 drivers/media/usb/uvc/uvc_driver.c |  8 ++++++++
 drivers/media/usb/uvc/uvcvideo.h   |  1 +
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index e59a463c2761..1951e06527cf 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1322,10 +1322,23 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
 		break;
 	}
 
-	if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN)
+	if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN) {
 		v4l2_ctrl->minimum = mapping->get(mapping, UVC_GET_MIN,
 				     uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN));
 
+		if (chain->dev->quirks & UVC_QUIRK_OBSBOT_MIN_SETTINGS) {
+			switch (v4l2_ctrl->id) {
+			case V4L2_CID_ZOOM_CONTINUOUS:
+			case V4L2_CID_PAN_SPEED:
+			case V4L2_CID_TILT_SPEED:
+				v4l2_ctrl->minimum = -1 * mapping->get(mapping, UVC_GET_MAX,
+						     uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));
+			default:
+				break;
+			}
+		}
+	}
+
 	if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX)
 		v4l2_ctrl->maximum = mapping->get(mapping, UVC_GET_MAX,
 				     uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));
@@ -1914,6 +1927,18 @@ int uvc_ctrl_set(struct uvc_fh *handle,
 				   uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN));
 		max = mapping->get(mapping, UVC_GET_MAX,
 				   uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));
+
+		if (chain->dev->quirks & UVC_QUIRK_OBSBOT_MIN_SETTINGS) {
+			switch (xctrl->id) {
+			case V4L2_CID_ZOOM_CONTINUOUS:
+			case V4L2_CID_PAN_SPEED:
+			case V4L2_CID_TILT_SPEED:
+				min = max * -1;
+			default:
+				break;
+			}
+		}
+
 		step = mapping->get(mapping, UVC_GET_RES,
 				    uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES));
 		if (step == 0)
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index bbd90123a4e7..d4edc1adb11b 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -3120,6 +3120,14 @@ static const struct usb_device_id uvc_ids[] = {
 	  .bInterfaceSubClass	= 1,
 	  .bInterfaceProtocol	= 0,
 	  .driver_info		= UVC_INFO_META(V4L2_META_FMT_D4XX) },
+	/* OBSBOT pan, tilt, zoom min settings quirk */
+	{ .match_flags		= USB_DEVICE_ID_MATCH_VENDOR
+				| USB_DEVICE_ID_MATCH_INT_INFO,
+	  .idVendor		= 0x3564,
+	  .bInterfaceClass	= USB_CLASS_VIDEO,
+	  .bInterfaceSubClass	= 1,
+	  .bInterfaceProtocol	= 0,
+	  .driver_info		= UVC_INFO_QUIRK(UVC_QUIRK_OBSBOT_MIN_SETTINGS) },
 	/* Generic USB Video Class */
 	{ USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_UNDEFINED) },
 	{ USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, UVC_PC_PROTOCOL_15) },
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 6fb0a78b1b00..0e2f083a5c0e 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -73,6 +73,7 @@
 #define UVC_QUIRK_FORCE_Y8		0x00000800
 #define UVC_QUIRK_FORCE_BPP		0x00001000
 #define UVC_QUIRK_WAKE_AUTOSUSPEND	0x00002000
+#define UVC_QUIRK_OBSBOT_MIN_SETTINGS 0x00004000
 
 /* Format flags */
 #define UVC_FMT_FLAG_COMPRESSED		0x00000001

---
base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
change-id: 20240325-obsbot-quirk-fix-relative-ptz-speed-9ae4ef59d80a

Best regards,
-- 
John Bauer <johnebgood@securitylive.com>

Hi John,

On Mon, 2024-03-25 at 19:38 -0500, John Bauer via B4 Relay wrote:
> From: John Bauer <johnebgood@securitylive.com>
> 
> The OBSBOT series of cameras misreports the minimum relative
> pan_speed, tilt_speed and zoom_continuous v4l2 controls resulting
> in the inability to control the camera with finesse with an analog
> stick or other programmatic methods. This patch applies to all
> Remo (OBSBOT) vendor cameras with the vendor ID of 0x3564. If the
> vendor fixes the firmware this behavior should still remain valid.
> With this broad vendor fix when new devices are released the kernel
> module won't need to be modified. When the vendor fixes the firmware the
> device list can be modified with finer grained device filters.

I don't think they misreports the values.

The UVC 1.5 spec says:

The bPanRelative field is used to specify the pan direction to move. A
value of 0 indicates to stop the pan, a value of 1 indicates to start
moving clockwise direction, and a value of 0xFF indicates to start
moving counterclockwise direction. <<The GET_DEF, GET_MIN, GET_MAX and
GET_RES requests will return zero for this field.>>

The bTiltRelative field is used to specify the tilt direction to move.
A value of zero indicates to stop the tilt, a value of 1 indicates that
the camera point the imaging plane up, and a value of 0xFF indicates
that the camera point the imaging plane down. <<The GET_DEF, GET_MIN,
GET_MAX and GET_RES requests will return zero for this field.>>

The bZoom field indicates whether the zoom lens group is stopped or the
direction of the zoom lens. A value of 1 indicates that the zoom lens
is moved towards the telephoto direction. A value of zero indicates
that the zoom lens is stopped, and a value of 0xFF indicates that the
zoom lens is moved towards the wide-angle direction. <<The GET_MIN,
GET_MAX, GET_RES and GET_DEF requests will return zero for this
field.>>

So they can't report negative values for GET_MIN, therefore the GET_MIN
of bPanSpeed, bTiltSpeed, b(Zoom)Speed will be the minimum speed of any
direction.

I think it will work with any PTZ camera without the quirk.

Regards,
Gergo