Raspberry Pi PoE HAT

[Ben Herrick]

Fedora ARM mailing list,

I've been trying to get the fan on my Raspberry Pi PoE HAT working with
Fedora 35 and 36 Beta. I'm using the aarch64 raw image.

I came across the instructions on the wiki page
here: https://fedoraproject.org/wiki/Architectures/ARM/Raspberry_Pi/HATs#PoE_Hat

Unfortunately, the line in config.txt from the wiki didn't work for me.

The lines that did work on Fedora 36 Beta for aarch64 are below:

dtoverlay=i2c
dtoverlay=pwm-raspberrypi-poe

I'm also able to set the fan parameters with the below:

dtparam=poe_fan_temp0=70000,poe_fan_temp0_hyst=10000
dtparam=poe_fan_temp1=60000,poe_fan_temp1_hyst=10000
dtparam=poe_fan_temp2=50000,poe_fan_temp2_hyst=10000
dtparam=poe_fan_temp3=40000,poe_fan_temp3_hyst=10000

Note that these same lines didn't work for me on Fedora 35 aarch64.

I'm hoping others can replicate my experience and the wiki can be
updated to help others.

Please let me know if you have any questions or concerns.

-Ben Herrick

[Brad Smith]

Fedora Arm Community -

Ben Herrick and I exchanged several messages about Fedora 36 and
Fedora 35. I was successful in getting the POE Hat fan to work with
Fedora 36 (beta) using a couple of the steps as outlined in the Fedora
wiki for RPI Hats but was not as successful with Fedora 35. I suspect
it should work as long as current firmware files are used (e.g.
start4.elf) but in my very limited testing with FC35, I could not get
the board to boot and I was too lazy to pull the headless board from
the rack to plug a monitor and keyboard to see where the boot was
stalling.

My original process involving a custom upstream device tree to
integrate with the POE Hat fan device driver still works fine for FC35
and FC34.

For Fedora 36 (beta) I found that if I followed the steps in the wiki
to load the firmware device tree (rm /boot/dtb and set FirmwareDT=true
in /etc/u-boot.conf) then the POE Hat fan would just work as long as I
also made sure the upstream_kernel=1 option in config.txt was
commented out.

I did not need to add the rpi-poe or i2c dtoverlay lines to
config.txt. This process worked on 3 RPi4 boards that were updated
from FC35 using dnf system upgrade and which use u-boot. A fourth RPi4
using UEFI was also updated to FC36 beta with upstream_kernel=1
commented out and the POE Hat fan also worked without any additional
configuration.  All 4 boards are 8 GB and all 4 POE Hats are the
original model.

The device tree can be inspected at /proc/device-tree and will show a
directory called pwm-fan which is the hook needed for the upstream fan
device driver. lsmod can be used to display the presence of the
pwm_raspberrypi_poe device driver that makes all of this happen as
long as the linux kernel is 5.13 or newer (if i recall correctly).

Glad to answer any questions.

regards

Brad

On Mon, Apr 18, 2022 at 7:15 AM Ben Herrick  wrote:
> Fedora ARM mailing list,
>
> I've been trying to get the fan on my Raspberry Pi PoE HAT working with Fedora 35 and 36 Beta. I'm using the aarch64 raw image.
>
> I came across the instructions on the wiki page here: https://fedoraproject.org/wiki/Architectures/ARM/Raspberry_Pi/HATs#PoE_Hat
>
> Unfortunately, the line in config.txt from the wiki didn't work for me.
>
> The lines that did work on Fedora 36 Beta for aarch64 are below:
>
> dtoverlay=i2c
> dtoverlay=pwm-raspberrypi-poe
>
> I'm also able to set the fan parameters with the below:
>
> dtparam=poe_fan_temp0=70000,poe_fan_temp0_hyst=10000
> dtparam=poe_fan_temp1=60000,poe_fan_temp1_hyst=10000
> dtparam=poe_fan_temp2=50000,poe_fan_temp2_hyst=10000
> dtparam=poe_fan_temp3=40000,poe_fan_temp3_hyst=10000
>
> Note that these same lines didn't work for me on Fedora 35 aarch64.
>
> I'm hoping others can replicate my experience and the wiki can be updated to help others.
>
> Please let me know if you have any questions or concerns.
>
> -Ben Herrick
>
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