Hi.

I've tried these changes (see more details in #6 ) and they worked.

I've tried in 3 consoles:
-In my 8gb Wii U and in one of my 32gb Wii U worked when turning ON the console with the Pi already connected trough USB;
-In another one of my 32gb Wii U worked, but not with the Pi already connected, it only worked when I connected the USB around the time the CD drive ends it's noises and around the time the "Wii U" logo shows on TV.

I'm attaching photos of the consoles I tried (I've also submitted this information to the database).
8gb console:

32gb console that won't boot with PI connected to USB before turning ON:

32gb console that boots to Recovery Menu with PI connected to USB before turning ON:

Although on one console it didn't work as expected, I think it's still a great and very welcome improvement.

Update to my last comment:
In my 32gb Wii U that worked when turning ON the console with the Pi already connected trough USB, after turning ON ColdBoot Tiramisu/Aurora, it stopped working, just like my other 32gb Wii U.
My other 32gb Wii U already had ColdBoot Tiramisu/Aurora ON.
Maybe the cause for the problem is in autobooting Tiramisu/Aurora.
I will make more tests, as soon as I find time...

Okay, I have made more tests :)

In a Wii U booting into the Health And Safety app, the changes made by V10lator don't work if the PI is connected to the USB before turning on the console :(
If I change the booting option of the console to the Wii U Menu, the V10lator's changes works great.

So, in conclusion, there is nothing wrong with my three Wii U consoles, there is nothing wrong with UDPIH and there is nothing wrong with the changes made by V10lator.

I hope that in the future someone will make more changes to make UDPIH also work with the PI connected to the USB before turning on the console in consoles coldbooting tiramisu/aroma.

Another find I made, I couldn't boot into the recovery_menu if I have a USB hard drive connected to the console.

Any update on why this hasn't been merged yet?

Any update on why this hasn't been merged yet?

Probably because it doesn't work in all use cases, and is a pretty hacky fix (just adds a delay)