Fan control

@jnettlet Can you provide more details on how to control the fan speed?

With the raw OS image I have been using so far the fan keeps running at full speed after boot, which is fine with me (at least once I had replaced the awful fan that came with the board…). However, an interesting side effect of switching from a raw image to a u-boot one is that the fan reduces speed before control is transferred to the OS:

## Booting kernel from Legacy Image at 80200000 ...
   Image Name:   
   Created:      2022-08-03  10:40:09 UTC
   Image Type:   AArch64 Linux Kernel Image (uncompressed)
   Data Size:    16147312 Bytes = 15.4 MiB
   Load Address: 80200000
   Entry Point:  80200800
   Verifying Checksum ... OK
## Flattened Device Tree blob at 80100000
   Booting using the fdt blob at 0x80100000
   Loading Kernel Image
   Loading Device Tree to 000000009fff1000, end 000000009ffff036 ... OK
Releasing fan controller full speed gpio
fsl-mc: DPL not deployed, DPAA2 ethernet not work

While I appreciate the reduced noise, I’m a bit hesitant to do kernel development with the fan not working at full speed (can never tell when something is going to go wrong…).

–Elad