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memset
Contributor
Contributor
2,867 Views
Registered: ‎12-23-2009

iMPACT's severe TCK frequency derating under Linux

Hello all! I'v posted that before in Design Tools section, but I'm afraid no one is reading that forum...

 

Every time i try to use Lab tools under Linux with DLC9G USB cable I stumble to TCK frequency derating.

I set the desierd frequency of 12Mhz in Cable setup, but on any JTAG command iMPACT limits the maximum speed to 750Khz:

 

Warning: Chain frequency (1000000) is less than the current cable speed (12000000).
 Adjust to cable speed (1000000).
Maximum TCK operating frequency for this device chain: 1000000.

There are no derating under Windows. I believe its a flaw of iMPACT's speed detection algorithm under Linux.

 

On Linux, Platform Cable USB works via iMPACT's native libusb inferface. I'v tried several versions of Lab tools, from 13.x to 14.4 with the same result and several PCs from powerful desktop to a tiny laptop with any type of JTAG target device I have the same result.

In any setup I'v tried: Windows - 12MHz, Linux - 1Mhz (750Khz).

 

Funny thing, even inside a virtual machine on Linux host Windows works properly with 12MHz TCK. If I try to use Windows virtual machine on VMWare running on the Linux host and the same target board with Platform Cable's USB port routed to VM, I enjoy the 12MHz speed. The same host running native Linux version of iMPACT gives me depressing 750Khz. That's very annoying.

So far, I never saw anything better than 750Khz under pure Linux. How can I fix it? Is it possible to disable the speed checking algo in iMPACT?

Thank you.

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memset
Contributor
Contributor
2,846 Views
Registered: ‎12-23-2009

Looks like only iMPACT is derating the frequency to 1M under Linux. xmd (fpga -f) works properly w/o any derating.

How to fix the iMPACT now? I need to turn off or repair the speed setting algo.

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