rk3399: uart2 crippled signal on tx @115200

[Chris Ruehl]

On 18/6/2020 6:10 pm, Chris Ruehl wrote:
> Hi,
> 
> I run into a strange thing on our customized RK3399-LPDDR4 using the UART2 
> @115200 the
> console spits bad charters. Checking the signal at the TX explains the reason, 
> the rising edge
> is very slow, (we checked with the scope).
> Set the GPIO4_C4 to pcfg_pull_up_20am not working.
> 
> Kernel: 5.4.40-rt
> Uboot: 2020-4
> 
> The strange observation:
> U-boot TPL boot , return to Boot-rom and the 1st
> lines from SPL (show uboot version) have a sharp rising edge as expected.
> 
> Anyone?  I don't know anymore.
> 
> Regards
> Chris


Solved. rk3399 io_domain problem supply 3.3v for all rails.
one was configured for 1.8v and that confused the rk808 had
reverence voltage on the uart block 2.5v not 1.5v.

all good now.

Chris