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Tegra USB host driver registry settings

Power enable pin settings​

This config is available from Image Version 0.1Beta 9 and onwards. The power enable pin settings can only be done on a global level. As the loading order of the USB host ports can change we have to define the keys in all of the USB host configs (USBEHCI1, USBEHCI2, USBEHCI3).


[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\USBEHCI(1/2/3)]
   "SodimmPen"=dword:0x00000081       ; Power enable SODIMM pin, defaul pin is SODIMM Pin 129.                   
   "PenPol"=dword:0x00000000          ; Power enable polarity, default 0 (Low Active)

Hotplug Delay​

Some USB devices are not recognized when they are plugged in during runtime. Sometimes it helps to increase the delay between plugin and setting up communication pipe by adding the key HotPlugDelayMS. Add the key to the required USBEHCI device (1/2/3). A typical delay of 100 ms is required for some USB devices. This feature is supported since image 1.3 beta 3. 


[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\USBEHCI(1/2/3)]
   "HotPlugDelayMS"=dword:0   ;Delay between plugin in the device and opening communication pipe in MS, default 0 ms.

Transmit Fifo Threshold​

This config is available from Image Version 2.1b2 and onwards. In some cases the USB client devices failed because of a buffer under run. Therefore we have introduced a way to increase the Transmit fifo threshold. This value actually defines how much data must be in the FIFO before the data is put on the USB lines. 


[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\USBEHCI(1/2/3)]
   "TxFifoThreshold"=dword:0x10   ; Transmit FIFO Threshold. Default 0x10; Min: 0x0, Max: 0x3F



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