LS1046A: How to power down a core

[scottwelsh]

Per my system requirements I need to power down 3 of the 4 cores. Can someone point me to the documentation which discusses how to shut down the specific clocks for 3 of the 4 cores?

Thank you

[Daves_Garage]

Hi Scott,  I just was looking into doing this myself when I ran across this unanswered question... I've sort of given up on this forum, as no one seems to respond for a really long time... looks like you asked your question over 5 months ago with no response.

Well, to show you what I did, here's a shot of my notes:

DISABLING CORES ON LS1046A

ref: 12.3.11 Core Disable Register (COREDISR)

• COREDISR provides a mechanism for gating clocks to any cores on the device that are not used when running an application.
• COREDISR register should only be configured in the following conditions:
  • Before system ready, COREDISR register can be programmed by the external debugger or Pre-Boot Initialization.
  • After system ready, a COREDISR register bit can be programmed for the corresponding core by the external debugger or embedded software while the core is in boot-holdoff mode.

HOW TO…

• DCFG_CCSR base address: 0x01EE0000
• COREDISR address: 0x01EE0094

Value Definition

0x000000002	Core 1 disabled
0x000000004	Core 2 disabled
0x000000008	Core 3 disabled

Values can be OR’d together to disable multiple cores.

Core 0 is always enabled…

Example:

    //-------------------------------------------------------------------------
    // disable core 3 and 2 so we only use core 0 and 1...
    //-------------------------------------------------------------------------
    write 0xEE0094, 0x0000000C

MODIFY U-BOOT TO REFLECT IDLE CORES

• Change code in ./u-boot/arch/arm/cpu/armv8/fsl-layerscape/cpu.c

for_each_cpu(i, core, cpu_numcores(), cpu_mask()) {
    if(!(i % 2)) 
        printf("\n\t");

    type = TP_ITYP_VER(fsl_qoriq_core_to_type(core));

    printf("CPU%d(%s):%-4s MHz %s ", core,
           (type == TY_ITYP_VER_A7) ? "A7 " :
              (type == TY_ITYP_VER_A53 ? "A53" :
              (type == TY_ITYP_VER_A57 ? "A57" :
              (type == TY_ITYP_VER_A72 ? "A72" : "   "))),
              strmhz(buf, sysinfo.freq_processor[core]),
              (in_be32(0x01EE0094) & (1<<core)) ? "[ IDLE ]" : "[ACTIVE]");
    }