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BQ25798: cannot enable PVT on the BQ25798 charging ship

Part Number: BQ25798

Tool/software:

I am having trouble configuring the BQ35798 charger. I am trying to enable the MPPT bit so that PVT charging can be allowed but for some reason the i cannot enable the EN_MPPT bit, it refuses to keep the change. I have to configuration output log below. Let me know if i am missing anything. the documentation mentions this 

For the EN_ICO, FORCE_VINDPM_DET and EN_MPPT three register bits, only one of them can be set to 1 at a given time. If one of them is enabled, the charger will block the host from enabling the other two features until the first is disabled.

and they are 0 by default. so i should be able to set the MPPT bit  but my log output tells me otherwise. any idea of what could not allow me to enable the EN_MPPT

[00:00:00.012,115] <dbg> bq25798_charger: initialize_charger_control_regs: Charger registers reset successfully.
[00:00:00.013,031] <dbg> bq25798_charger: initialize_charger_control_regs: Min system voltage: 0x9C4
[00:00:00.015,991] <inf> bq25798_charger: Charge current limit set successfully.
[00:00:00.016,601] <inf> bq25798_charger: Charge voltage limit register value before: 0xA401
[00:00:00.016,601] <inf> bq25798_charger: Charge voltage limit register value after: 0xA401
[00:00:00.017,639] <dbg> bq25798_charger: initialize_charger_control_regs: Part number: 0x03, Revision: 0x01
[00:00:00.020,416] <inf> bq25798_charger: NTC control register value for TS_IGNORE: 0x1
[00:00:00.020,416] <inf> bq25798_charger: Setting NTC control 1
[00:00:00.020,965] <inf> bq25798_charger: NTC control register value before: 0x54
[00:00:00.020,965] <inf> bq25798_charger: NTC control register value after: 0x55
[00:00:00.021,881] <inf> bq25798_charger: Charger control 1 register value before: 0x85
[00:00:00.021,881] <inf> bq25798_charger: Charger control 1 register value after: 0x80
[00:00:00.021,911] <inf> bq25798_charger: Setting charger control 1
[00:00:00.022,827] <inf> bq25798_charger: Input voltage limit register value before: 0x2E
[00:00:00.022,827] <inf> bq25798_charger: Input voltage limit register value after: 0x31
[00:00:00.023,834] <inf> bq25798_charger: Input current limit register value before: 0x2C01
[00:00:00.023,864] <inf> bq25798_charger: Input current limit register value after: 0x6400
[00:00:00.024,871] <inf> bq25798_charger: Charger control 0 register value before: 0xA2
[00:00:00.024,902] <inf> bq25798_charger: Charger control 0 register value after: 0xA2
[00:00:00.024,902] <inf> bq25798_charger: Setting charger control 0
[00:00:00.025,299] <inf> bq25798_charger: Setting charger control 2
[00:00:00.026,214] <dbg> bq25798_charger: bq25798_set_mppt_control: MPPT control register value before: 0xAA
[00:00:00.026,214] <dbg> bq25798_charger: bq25798_set_mppt_control: Going to set MPPT control register value to: 0x6B
[00:00:00.027,160] <dbg> bq25798_charger: bq25798_set_mppt_control: MPPT control register value after: 0x6A
[00:00:00.027,160] <inf> bq25798_charger: BQ25798 charger initialized