Re: USB output in ucom

[Emmanuel Dreyfus <manu%netbsd.org@localhost>]

On Sun, Jul 13, 2025 at 06:07:56AM -0000, Michael van Elst wrote:
> You could try to dump the bytes you receive instead of deducing
> them from the visible output.

Using ktrace on screen, on the receiving end:
" "
"EL"
"L"
"O"
" "
"W"
"O"
"RL"
"D"
"!\r\n"
"X"
"x"

On first insight, I thought the first output was just discarded
and the trailing x was just there because the same buffer was used.

But on first output I give usbd_setup_xfer() a 16 characters length,
on second output, 15 characters. I cannot make up an explanation why
the trailing x is there. Perhaps the receiving kernel does some
processing?

> If that's real hardware, I'd guess that the symptoms come from
> a hardware problem like a missing ground.

The link works find with other usages.

-- 
Emmanuel Dreyfus
manu%netbsd.org@localhost