USBCECAdapterDetection: Limit scan to tty subsystem #494
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fritsch
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While debugging high CPU load coming from PeripUSBCEC thread I figured that the library call: DetectAdapters hoggs the CPU for up to 200 ms per Call. Looking into it I spotted that the usb udev enumeration and scanning happens on every device in /sys
Therefore: Limit device comparison for the tty subsystem only. This reduces comparisons by factor 4. 100 tty-devices vs. 400 devices in sum. It's a pitty that we need to start with the leafs and then query over the parent.
Runtime tested on LibreELEC.