Original question:
TPS65217: How to modify a register value using the Linux driver
Dear Expert
At present, TPS65217 power supply chip is used in the project, so the output voltage of VDD_MPU（DCDC2） needs to be set as 1.25V, and the default is 1.1V. It can be realized by the DCDC2 control register set in the specification, but it will not take effect after writing. The measured voltage is still 1.1V, please help to check.
Hi Gabriel,
Thank you for reaching out via E2E. The write of 00001110b to DEFDCDC2 register (address 0x0F hex) shown in your attached code is correct to set DCDC2 to 1.25V output.
Please be aware this device uses password protection to prevent accidental writing of specific registers. The DCDC2 control register is level2 password protected, as shown in figure 29 on page 44 of the datasheet. Are you currently following the steps listed in section 8.5.22 Level2 Protection on page 43 and shown below?
The register will only update from 1.1V to 1.25V if all steps are correctly followed and no other I2C transactions occur between step 2 and step 5 of section 8.5.2.2.
Best Regards,
Garrett
