Is it possible to turn off one ARM Cortex-A7 Core in the LS1021A to reduce power?

[nikhilrao]

From looking at the reference manual Rev 0 (5 Nov 2015), I found the description of a Boot Release Register DCFG_CCSR_BRR on page 554.

If we would like to switch off one processor core, is modification of this register (thru RCW) the only means to achieve this?

We are using the TWR-LS1021A-PB evaluation board (currently with v1.8 SDK).  Once the LS1021A boots up (from either NOR or SD Card), we find the temperature of the CPU Heatsink gets to around 68 deg C (in an ambient room temperature of around 25 deg C).  This is just after around 15 to 20 minutes of the board being powered. Linux had booted up and no user applications were running, apart from “top”.  

Is it normal for the LS1021A CPU Heat Sink to get this hot and have over 40 degrees C temperature rise above ambient with practically no apps running?

Kind Regards,

Nikhil

[ufedor]

> is modification of this register (thru RCW) the only means to achieve this?

Yes - for available options please refer to the QorIQ SDK 1.9 Documentation, Power Management User Manual:

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[nikhilrao]

Thank you Ufedor.  I will request the Power Management User Manual from our NXP contacts.  I have downloaded the CORTEXA7 related SDK 1.9 files (nearly 15 Gigabytes).  But after a quick scan I don't see this Power Management User Manual in the downloaded files.

Could you comment on the temperature rise of the LS1021A Heat Sink (on TWR-LS1021A or TWR-LS1021A-PB)?  We are seeing over 40 degrees C temperature rise above ambient, with practically nothing running (just sitting at Linux prompt).

CPU Heatsink gets to around 68 deg C, in an ambient room temperature of around 25 deg C. Is this normal?

[nikhilrao]

Hi Ufedor,

I now have the QorIQ SDK 1.9 Documentation.  I'll read thru the relevant Power Management chapter.

However could you please comment on the LS1021A's temperature rise (in the TWR-LS1021A-PB), as raised in my two previous posts.

Thanks,

Nikhil