[sane-devel] Color managment `colord-sane` on Ubuntu 20.04 switches off USB-Port

[Ulf Zibis]

Hi,

I have the slide scanner "Braun MultiMag SlideScan 6000" here. When I connect it, the process `colord-sane` is started during its approx. 3-minute self-calibration, which then disappears again. After that, the device is no longer listed via `lsusb`, so presumably the USB port is switched off. During the 3 minutes it is still there:
$ lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 8087:8008 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 002: ID 8087:8000 Intel Corp. Integrated Rate Matching Hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 002: ID 046d:c05a Logitech, Inc. M90/M100 Optical Mouse
Bus 003 Device 003: ID 8087:07dc Intel Corp. Bluetooth wireless interface
Bus 003 Device 004: ID 04ca:7035 Lite-On Technology Corp. Integrated Camera
Bus 003 Device 014: ID 05e3:0142 Genesys Logic, Inc. Multiple Slides Scanner-3600
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub

I use the VueScan program to use the scanner. If I start it during or after self-calibration, the scanner is not found

The only way to connect VueScan to the scanner and then use it is to connect the scanner to USB only after self-calibration. However, this obviously prevents the use of colour management. What consequences could this have?

In my humble opinion, it should not be the task of the SANE colour management to switch off USB ports.
Could this be a bug? How can this be prevented?

What do you think?

-Ulf

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