sample-photobooth not setting correct shutterspeed

[reedev]

Hi,

I would like to ask your help about setting the shutterspeed for an application like sample-photobooth. When I try to set the config via the config.txt with line
shutterspeed=1/500
it is parsed ok and applied, according to the printed feedback. However, the shutterspeed is not correctly applied to the device. Reading the config file multiple times in a row applies different (random so it seems?) values.

When I run for instance
gphoto2 --set-config shutterspeed="1/320"
the value is applied correctly.

Name the camera
Sony DSC-RX100M7 (PC Control) usb:001,030

libgphoto2 and gphoto2 version
gphoto2 2.5.28.1 gcc, popt(m), no exif, no cdk, no aa, jpeg, no readline
libgphoto2 2.5.30.1 standard camlibs (SKIPPING docupen), gcc, no ltdl, no EXIF
libgphoto2_port 0.12.2 iolibs: disk ptpip serial usb1 usbdiskdirect usbscsi, gcc, no ltdl, no EXIF, USB, serial without locking

(built just now from current master branch)

To Reproduce
See above, running sample-photobooth

0.000060 main (2): ALWAYS INCLUDE THE FOLLOWING LINES WHEN SENDING DEBUG MESSAGES TO THE MAILING LIST:
0.000072 main (2): gphoto2 2.5.28.1
0.000075 main (2): gphoto2 has been compiled with the following options:
0.000077 main (2): + gcc (C compiler used)
0.000080 main (2): + popt (mandatory, for handling command-line parameters)
0.000082 main (2): + no exif (for displaying EXIF information)
0.000084 main (2): + no cdk (for accessing configuration options)
0.000086 main (2): + no aa (for displaying live previews)
0.000088 main (2): + jpeg (for displaying live previews in JPEG format)
0.000090 main (2): + no readline (for easy navigation in the shell)
0.000096 main (2): libgphoto2 2.5.30.1
0.000098 main (2): libgphoto2 has been compiled with the following options:
0.000101 main (2): + standard camlib set SKIPPING SOME (ax203 canon digigr8 dimagev directory jl2005a jl2005c kodak_dc240 lumix mars pentax ptp2 ricoh_g3 sierra sonix sq905 st2205 topfield tp6801 SKIPPING docupen)
0.000106 main (2): + gcc (C compiler used)
0.000108 main (2): + no ltdl (for portable loading of camlibs)
0.000112 main (2): + no EXIF (for special handling of EXIF files)
0.000117 main (2): libgphoto2_port 0.12.2
0.000121 main (2): libgphoto2_port has been compiled with the following options:
0.000124 main (2): + iolibs: disk ptpip serial usb1 usbdiskdirect usbscsi
0.000126 main (2): + gcc (C compiler used)
0.000128 main (2): + no ltdl (for portable loading of iolibs)
0.000131 main (2): + no EXIF (for vusb)
0.000133 main (2): + USB (libusb1, for USB cameras)
0.000136 main (2): + serial (for serial cameras)
0.000139 main (2): + no resmgr (serial port access and locking)
0.000141 main (2): + no ttylock (serial port locking)
0.000143 main (2): + no lockdev (serial port locking)
0.000146 main (2): CAMLIBS env var not set, using compile-time default instead
0.000149 main (2): IOLIBS env var not set, using compile-time default instead
0.000152 main (2): invoked with following arguments:
0.000155 main (2): --debug
0.000164 load_settings (2): Creating gphoto config directory ('/home/ray/.gphoto')
0.000191 load_settings (2): Loading settings from file '/home/ray/.gphoto/settings'.
0.000250 gp_camera_free (2): Freeing camera...
0.000254 gp_port_free (2): Freeing port...
0.000258 gp_filesystem_reset (2): resetting filesystem
0.000260 gp_filesystem_lru_clear (2): Clearing fscache LRU list...
0.000262 gp_filesystem_lru_clear (2): fscache LRU list already empty
0.000264 delete_all_folders (2): Internally deleting all folders from '/'...
0.000267 lookup_folder (2): Lookup folder '/'...
0.000269 lookup_folder (2): Found! / is 0x55edcb8a98b0
0.000271 recurse_delete_folder (2): Recurse delete folder 0x55edcb8a98b0//
0.000274 delete_all_files (2): Delete all files in folder 0x55edcb8a98b0//

Any idea what's going on? Any tip/hint is welcome to investigate the issue.

Cheers,
Raymond