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Observer pd92
Observer
2,160 Views
Registered: ‎08-29-2017

ZCU102: Switch off programmable logic while PS active

In order to reduce the ZCU102 power consumption, is it possible to powerdown the programmable logic while keeping the PS active using some Petalinux command?

It would be something similar to echo mem > /sys/power/state for the Cortex-A53 processors, but applied to the PL side of the board. Using Maxim Power Tool it seems that the PL consumes power (static) even when it is not used or initialized.

Regards 

 

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4 Replies
Voyager
Voyager
2,137 Views
Registered: ‎06-24-2013

Re: ZCU102: Switch off programmable logic while PS active

Hey @pd92,

 

is it possible to powerdown the programmable logic while keeping the PS active

There are different levels of power saving you can apply ...

  • Load a design which has minimal power consumption.
  • Disable the level converts and PL interfaces.
  • Power down Vccint and thus the entire PL.

using some Petalinux command?

something similar to echo mem > /sys/power/state

I don't think that there is something as simple as this to power down the entire PL, but I might be wrong there.

I'm not even sure you can control Vccint on the ZCU102 from Linux, but I didn't investigate this yet.

 

Hope this helps,

Herbert

-------------- Yes, I do this for fun!
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Observer pd92
Observer
2,087 Views
Registered: ‎08-29-2017

Re: ZCU102: Switch off programmable logic while PS active

Hi Herbert,

thanks for your answer. My idea is to minimize the power consumption of the PL side when it is not used, without the need of reloading the bitstream for short periods, or even reloading the bitstream if the period in which the PL is not used is enough long. In this case, the from you mentioned third alternative would be the most interesting, if there is a way to implement it runtime directly by software.

 

Another point, always in the view of reducing power consumption. I tested the following instructions:

    echo enabled > /sys/devices/platform/amba/ff000000.serial/tty/ttyPS0/power/wakeup
    echo mem > /sys/power/state

and verified using the Maxim PowerTool that the power consumption goes effectively almost to zero, as the entire PS is in a powerdown state. Everything ok.

 

Conversely, I realized with the PowerTool that the following command, related to the CPU hotplug, has no appreciable influence on power consumption:

  echo 0 > /sys/devices/system/cpu/cpu3/online

even when three out of four CPUs are offline. I verified that the CPUs are offline (both using xsdb where they appear as not running anymore and using the simple linux "top" command, in which the CPUs are not listed anymore as soon as the command is launched). Indeed the current floats around 1.2/1.3 A, the same as when all the processors are active without doing any operation.

May this a problem related to the petalinux configuration/drivers or an hardware issue in the ZCU102 board?

The instruction is taken from:

http://www.wiki.xilinx.com/Zynq+UltraScale%EF%BC%8B+MPSoC+Power+Management+-+Linux+Kernel

and the kernel configuration options have been correctly set. Instead, the cpufrequency regulation works perfectly fine.

Regards

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Observer pd92
Observer
2,032 Views
Registered: ‎08-29-2017

Re: ZCU102: Switch off programmable logic while PS active

In addition to what already said, there is an inconsistency between the measurement using Maxim Power Tool and the SCUI (System Controller) application, for what concerns the PL logic power measurement.

Using the second method, the current on the VCCINT pin (programmable logic) is always around 0.16A. Instead, the PowerTool from Maxim reports that the current floats between 0.2 and 0.6 A, when the FPGA fabric is not programmed. Instead, when I programmed it with a simple matrix multiplication program, according to SCUI is the current around 0.6 A, while the Powertool measured values vary between 1.4 A and 1.8 A. The same at execution time, where the values are respectively 1.4A and 2.5/4 A.

What may be at the origin of this difference, which appears only in reference to the PL and not the PS?

By the way, I checked out that even using the SCUI it seems that the CPU hotplug command

  echo 0 > /sys/devices/system/cpu/cpu3/online

has no effect on power consumption .

Regards

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Contributor
Contributor
1,248 Views
Registered: ‎04-19-2018

Re: ZCU102: Switch off programmable logic while PS active

I'm in the same boat and would like to have the full power domain powered APUs, and the PL logic turned off.

In my implementation the PL will be ~consuming around 90% of the power..

 

pd92, did you ever get any of your options implemented?

I'm specifically keen on powering down the VCCINT, if possible?

 

Thanks in advance

Tim

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