SPI3 can be used as wakeup source for exit from PowerDown mode. And it works fine.
But RX fifo has size 8 items only and wakeup take > 350 us.
It means , MCU can't receive any more bytes until SPI ISR can be processed.
So I shouln't expect if more than 8 items will be in Fifo until exit from PowerDown is fully completed.
Is this so ? Or for wakeup more RX fifo can be allocated some how ?