In Bosch Sensortec | BMI270 Data sheet:
page 110 - Register (0x42) GYR_CONF says that odr_6k4 is reserved.
page 2 says: Output data rates (ODR): 25 Hz ... 6.4 kHz (gyroscope) and 0.78 Hz ... 1.6 kHz (accelerometer)
How can I set odr_6k4 for gyro ?
If gyro ODR is 3k2 I'm getting about 60 interrupts per sec (with my watermark settings). If I chane ODR to 6k4 I'm getting about 24 interrupts per sec.
Technically, you need to clear 4th bit in 0x45 register.
But, this is not that all for your fifo setting.
Therefore, I don't recommend to develop BMI270 w/o API. (If now, you are using our BMI270 API, that's great!)
Please BMI270 API as below URL.
And here is the my gyro fifo 6.4k ODR example code as attaced file.