# How to disable/control M7 cpu on i.MX8MP?

**URL:** <https://community.solid-run.com/t/how-to-disable-control-m7-cpu-on-i-mx8mp/723>\
**Category:** NXP i.MX8M Plus\
**Created:** [September 14, 2023, 12:31pm UTC](https://community.solid-run.com/t/how-to-disable-control-m7-cpu-on-i-mx8mp/723 "2023-09-14T12:31:43Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![pflander](https://avatars.discourse-cdn.com/v4/letter/p/35a633/32.png) [@pflander](https://community.solid-run.com/u/pflander)\
**Post date:** [September 14, 2023, 12:31pm UTC](https://community.solid-run.com/t/how-to-disable-control-m7-cpu-on-i-mx8mp/723/1 "2023-09-14T12:31:43Z")

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We want to optimize power consumption and as we don’t use M7 cpu at the moment we want to disable it.  
Which steps do we need to take?

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**Author:** ![jnettlet](https://dub1.discourse-cdn.com/flex005/user_avatar/community.solid-run.com/jnettlet/32/62_2.png) [@jnettlet](https://community.solid-run.com/u/jnettlet)\
**Post date:** [September 15, 2023, 2:26am UTC](https://community.solid-run.com/t/how-to-disable-control-m7-cpu-on-i-mx8mp/723/2 "2023-09-15T02:26:21Z")

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By default the core should be held in WFI mode until it is initialized and firmware is uploaded to it. However you can control it through NXP’s SMCCC calls from u-boot.

arm\_smccc\_smc(IMX\_SIP\_SRC, IMX\_SIP\_SRC\_M4\_STOP, 0, 0, 0, 0, 0, 0, &res);

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<div class="post-metadata">

**Author:** ![pflander](https://avatars.discourse-cdn.com/v4/letter/p/35a633/32.png) [@pflander](https://community.solid-run.com/u/pflander)\
**Post date:** [September 15, 2023, 8:12am UTC](https://community.solid-run.com/t/how-to-disable-control-m7-cpu-on-i-mx8mp/723/3 "2023-09-15T08:12:47Z")

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When running command from u-boot I get the following error:

```auto
Hit any key to stop autoboot: 0
u-boot=> arm_smccc_smc(IMX_SIP_SRC, IMX_SIP_SRC_M4_STOP, 0, 0, 0, 0, 0, 0, &res);
syntax error

```

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<div class="post-metadata">

**Author:** ![jnettlet](https://dub1.discourse-cdn.com/flex005/user_avatar/community.solid-run.com/jnettlet/32/62_2.png) [@jnettlet](https://community.solid-run.com/u/jnettlet)\
**Post date:** [September 15, 2023, 8:21am UTC](https://community.solid-run.com/t/how-to-disable-control-m7-cpu-on-i-mx8mp/723/4 "2023-09-15T08:21:59Z")

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that isn’t a command. There is no user interface for this, it would need to be incorporated into the u-boot code.