Serial debug and 1500000 bps issue

Hi, funny problem, I have Prolific USB to TTL converter (typical cable). I was fighing a bit to make it working on my Win10 laptop.

I have connected it to header but can not see anything during boot time. As shown on the picture above
Later on, after boot completes, console on serial 9600 bps is working like charm.

And image with 9600 console

I have a

Works 150000000 no probs also have my original think that is a PL but nope it can not do that baud rate.

@stuartiannaylor, good to know. I will try to check with other converter. I stick to this PL, as it is a long cable one, looks like this:
I do believe it is PL2303HX. Hm, when checking now indeed it does not support that baud rate using “driver” - what does it mean, no idea…

Is that a 5v one or 3.3v one? Mine has a jumper to select the different logic levels.
Says “The programmable baud rate
generator supports baud rates up to 12M bps” which isn’t 1500000 bps?

Quote from wiki:

The default baudrate of ROCK Pi 4 is 1500000(1.5Mbps), please check if your USB to TTL cable support 1.5Mbps baudrate. Some model of CP210X and PL2303x have baudrate limitation, please check the specified model. We also tested that some cheap PL2303x based cable does not work well. Make sure choose a high quality one. The instructions below use a FT232RL based cable.

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Switched to converter with CH340 chip. Works.

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