I'm developing the custom carrier board for RK1 module. Can't find any corresponding docs (datasheet, design guide e.t.c). Even "Pinout compatible to Jetson" statement not clear enough as all 3 closest Jetson modules (Nano/Orin Nano/Orin NX) has different peripherals list and correspondingly different pinout . Is such documentation available?

I haven't found any official documentation. You might try sending an email to help@turingpi.com. Failing that, it should be possible to reverse engineer the RK1s pin mux by looking at the device tree definition and "pins" file in the u-boot source from the RK1-specific version of Ubuntu. They will be in the appropriate overlay(s).

Could you please advice where to find "u-boot source from RK1-specific version of Ubuntu"? I've checked an official u-boot repo ans Joshua's repos. While there are some hardware descriptions (and even pin-mux info), didn't find and info related to SODIMM pins. I have very basic understanding of u-boot so maybe missing something obvious...

The U-Boot source is a little strange in Ubuntu Rockchip due to packaging requirements on Launchpad. The changes made to U-Boot are in patch files and applied by quilt. For a quick rundown on how I populate a local U-Boot repo for the RK1:

bash
git clone https://github.com/Joshua-Riek/ubuntu-rockchip.git
git clone https://github.com/u-boot/u-boot.git
cd u-boot
git checkout cb493752394adec8db1d6f5e9b8fb3c43e13f10a

git am ../ubuntu-rockchip/packages/u-boot-turing-rk3588/debian/patches/0001-include-turing-rk1-rk3588-define-boot-targets.patch
git am ../ubuntu-rockchip/packages/u-boot-turing-rk3588/debian/patches/0002-arm-dts-rk3588-turing-rk1-fix-pcie3x4-hang.patch
git am ../ubuntu-rockchip/packages/u-boot-turing-rk3588/debian/patches/0003-arm64-dts-rockchip-Fix-eMMC-Data-Strobe-PD-on-rk3588.patch

As for compiled binary's they are all published on Launchpad with the source code included: https://launchpad.net/~jjriek/+archive/ubuntu/rockchip Also see: https://github.com/Joshua-Riek/ubuntu-rockchip/tree/8e21b8a53bd0fc97481ebe3c203a6b8b832ef1bc/packages/u-boot-turing-rk3588/debian

Thanks, but still can't find anything related to SODIMM pins there. There is some (looks like not all) SoC pins (including numbers, mux, pull mode), but no SODIMM. If it is there, or somewhere else, could you please point me to exact file?