I2C masters do not operate while the device is in deep-sleep mode. One of the I2C Slaves can operate in deep-sleep power mode.
Could you point us to where we could find more information on this? Thank you.
If you look at figure 2 you'll see that 1 of the SCBs is in light blue indicating that it works in deepsleep. Also the sub heading Serial Communication Block on page 8 makes mention of this as well:
Serial Communication Blocks (SCB) PSoC 63 has nine SCBs, which can each implement an I2C, UART, or SPI interface. One SCB will operate in Deep Sleep with an external clock, this SCB will only operate in Slave mode (requires external clock).
The TRM chapter on SCBs also mentions which modes work in deepsleep and how to configure the device:
Please note description in TRM "this is the only SCB that is available in the Deep Sleep power mode." means I2C / SPI slave wakeup available under DSM, not work directly under DSM, because mcu is not capable of handling data under DeepSleep mode. After waking up through address matching, device would get back to active mode for normal handling.