I don't know if I'm at the right forum if no I'm sorry.
I develop a product with Apollo Lake SoC, the power up sequence is going OK until the moment the SoC suppose to toggle the PLTRST_N.
One of the step that happen in the power up sequence is reading from the SPI flash CSE (the same like TXE).
The SoC is reading the descriptors from the SPI Flash and than stop.
Do you know if it something that can cause the TXE?
I saw in the INTEL Flash Image Tool a "OEM public key hash" does the SoC is checking it in the descriptor or only after the BIOS is running?
I have a key that I burn to the BIOS binary, how could I know that I am using the right one?
It has been some time since your post, and I am now having the same problem - SPI reading stops completely after reading the flash descriptor using Apollo Lake. I am also using the OEM public key hash that is recommended, but not sure if it is compatible with brand new, blank hardware (i.e. not sure it can be used during board bring-up). Have you had any success in solving your issue, and if so, how?
I suffering from same problem too. After reading the flash descriptor(0x148h), flash reading stopped.(I think that TXE Firmware may be loaded from flash into SRAM by TXE ROM.)
Did you find a solution?