Fixing the problem with PCIe/SATA on Rock 5 ITX

[sdyspb]

Dim Sidorovich, [2/16/2025 8:27 PM]
It seems I’ve found the main reason of SATA detected problem on Rock 5 ITX

For my opinion, it’s SRIS mode (Separated Reference Clock with Spread Spectrum Clocking) of ASM1164 that is enabled during start up. According to ASM1164 datasheet, pin 14 is a strap pin for SRIS_EN# and low level on it during start up enables the SRIS:

There is no SSC with clock generator chip or independent PCIe clock for controller, so maybe PLL of ASM1164 is not locked with SRIS:

There are pull up and pull down resistors on the board. These are R96000 and R29, respectively, but R29 is “stronger” than R96000, so pin 14 is pulled down:

The workaround is unsolder R29 that is on bottom side to pull up pin 14 by R96000:

Unsolder R29 with care. It actually needs good soldering iron. I use Ersa with 102ADLF20 tip at 370 Celsius because one terminal of R29 is on ground plane:

That’s all. I’ve tested the workaround on my board - works 10/10 after reboot and poweroff

[yppc]

R33 should disable PCIe SSC. So it should run with SRIS but without SSC. Can SRIS work without SSC (will it enable SRNS in that case)?

[sdyspb]

SRIC it’s about independent clock with SSC. Radxa 5 ITX uses Common Reference Clock, not SRIS, so it doesn’t matter whether SSC clock exists or not. The main reason not to use SRIS is a PCIe Common Clock schematic of the board

I’m absolutely sure that there is wrong pin-strap configuration of the ASM1164 and the only one right option is unsoldering R29