Custom module flash speed limitation

[Lucas.Hutchinson]

Hi All,

We have designed an ESP32 module.
We are currently going through some testing and have found that the chip will fail to boot properly if the SPI flash speed is set to anything above 20MHz.

The module fails on boot with the error detected as "rst:0x10 (RTCWDT_RTC_RESET),boot:0x17 (SPI_FAST_FLASH_BOOT)"
The last line of the logging output before the reset is: "load:0xffffffff,len:-1"

As mentioned in the title we are using the GD25Q32C (in the 3x3 USON8 package).
All the QSPI lengths are within 1.8mm length matched to the QSPI clock line.

Is anyone able to tell us what to look for with this sort of issue?

Thanks!
Lucas