[Fujifilm X-T3] LiveView locks parameter changes (fake GP_OK), and camera hangs in PTP_BUSY after capture

[edramigon-maker]

Hello libgphoto2 team,

First of all, thank you for your amazing work. I am developing an Android application using libgphoto2 (via JNI/C++) connected to a Fujifilm X-T3 via USB. I am facing a complex state-lock issue related to the LiveView and Capture flow.

Here are the two main issues I am experiencing:

Issue 1: Parameter changes are silently ignored after LiveView starts/stops

1. Initial connection: I initialize the camera. I can successfully change parameters (ISO, Aperture, Shutter Speed) using gp_widget_set_value and gp_camera_set_config.
2. Start LiveView: I start a loop calling gp_camera_capture_preview(). It works perfectly.
3. Stop LiveView: I break the loop to change a parameter.
4. The Bug: If I try to change a parameter now, gp_camera_set_config returns GP_OK (0), but the camera silently ignores it (if I read the config back immediately, the value hasn't changed).
   • What I've tried: I attempted to manually turn off the viewfinder using the Fujifilm vendor opcode 500b (set_config("500b", 0)), but the camera seems to ignore this opcode via USB. I also added gp_camera_get_summary() to force a state refresh, but the camera remains "locked" against parameter changes.

Issue 2: Post-Capture PTP_BUSY state anomaly

Following the LiveView issue, if I proceed to take a picture:

1. I stop the LiveView loop.
2. I call gp_camera_capture().
3. The image is captured and downloaded successfully, but the camera enters a "Busy" state (LED blinking green/orange) and gets stuck there.
4. The anomaly: Curiously, while in this stuck/busy state, parameter changes (ISO, Shutter) suddenly start working again. However, because it is stuck, I can no longer restart LiveView or take another picture.
   • What I've tried: I implemented a robust event-draining loop (gp_camera_wait_for_event), capturing GP_EVENT_FILE_ADDED, doing gp_camera_file_get (to satisfy Fuji's buffer) and gp_camera_file_delete. Even with this, the camera struggles to return to a clean idle state to resume LiveView.

Environment Details:

• Camera: Fujifilm X-T3 (Firmware: 5.11)
• Connection: USB Tethering Auto / USB to Android device.
• libgphoto2 version: 2.5.33
• OS: Android (using NDK/C++)

Is there a specific sequence of commands or PTP vendor extensions required for the X-T3 to properly exit the LiveView state and accept config changes? Also, how can I cleanly clear the PTP_BUSY state after a capture so LiveView can be resumed?

Any guidance or workarounds would be deeply appreciated. Thank you!