# Fan PWM status?

**URL:** <https://community.solid-run.com/t/fan-pwm-status/340>\
**Category:** NXP LX2160\
**Tags:** NXP-LX2160\
**Created:** [June 1, 2022, 11:51pm UTC](https://community.solid-run.com/t/fan-pwm-status/340 "2022-06-01T23:51:31Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![the\_n00b](https://avatars.discourse-cdn.com/v4/letter/t/8e8cbc/32.png) [@the\_n00b](https://community.solid-run.com/u/the_n00b)\
**Post date:** [June 1, 2022, 11:51pm UTC](https://community.solid-run.com/t/fan-pwm-status/340/1 "2022-06-01T23:51:31Z")

</div>

Kind of a follow-up from [this post](https://community.solid-run.com/t/fan-control/205).

PWM is not connected to the fan, but an OS with I2C support is supposed to be able to control the fan speed? I am using Linux with UEFI and exposed device tree (could not boot under ACPI), but the fan always runs at full speed. Kernel wants to use the amc6821 driver but the speed never changes when testing with pwmconfig or any other tool.

Is fan control not supported or am I missing something?

---

<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:** [June 2, 2022, 3:49am UTC](https://community.solid-run.com/t/fan-pwm-status/340/2 "2022-06-02T03:49:20Z")

</div>

device-tree under edk2 is not a supported configuration. That is still in the firmware only for development purposes. Under Linux fan control is implemented in AML via the thermal zone ACPI spec.

---

<div class="post-metadata">

**Author:** ![the\_n00b](https://avatars.discourse-cdn.com/v4/letter/t/8e8cbc/32.png) [@the\_n00b](https://community.solid-run.com/u/the_n00b)\
**Post date:** [June 2, 2022, 4:21am UTC](https://community.solid-run.com/t/fan-pwm-status/340/3 "2022-06-02T04:21:11Z")

</div>

Okay, good to know. With ACPI+edk2 though the kernel and initramfs cannot detect eMMC. Several relevant devices never show up and their drivers, though compiled in, are never loaded. Switching to device tree fixed that problem. Is there something different I am expected to do with ACPI?

---

<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:** [June 2, 2022, 4:26am UTC](https://community.solid-run.com/t/fan-pwm-status/340/4 "2022-06-02T04:26:03Z")

</div>

mainline has chosen not to merge the patches we need to support eMMC with ACPI. You either need to use our 5.15.y-cex7 kernel branch, or switch to u-boot with device-tree, and the vendor BSP or mainline kernel.