RE: [PATCH 2/2] rtc-tps65910: enable RTC power domain oninitialization

[Kim, Milo]

Hi Venu

> >  Enabling RTC HW block depends on the default value of TPS65910
> register.
> >  In some mode, RTC block is disabled by default.(eg. AM3517
> Craneboard)
> >  In this case, RTC_PWDN(RTC power down) bit should be cleared to
> enable
> >  the RTC HW block.
> 
> From the description of RTC_PWDN bit of DEVCTRL_REG in TPS65910 data
> sheet
> it is very evident that the default value of RTC_PWDN is 0.

According to the datasheet(http://www.ti.com/lit/ds/swcs046q/swcs046q.pdf),
the default value RTC_PWDN is 1 which means power down.

The default values are loaded from the EEPROM with BOOT_MODE 0,1 pin connection.
The RTC is disabled by default when BOOT_MODE = 00.
The Craneboard has the BOOT_MODE 00.

You may have other EEPROM settings,
however the official datasheet shows the RTC block is off by default.

Could you check the silicon version number? (0x80 register - JTAGVERNUM_REG)
In my case, the read value is 0x01.

> Probably on "AM3517 Craneboard", some code is running prior to the RTC
> driver
> which might be writing 1 on to this bit. IMO you must disable that
> write operation
> instead of just writing default value into a register.

Thank you for your comment.
I've read the DEVCTRL register (0x3F) in mfd tps65910 driver
as soon as the regmap registration is done, however RTC_PWDN is always 1.
That means the RTC is disabled by default.

Best Regards,
Milo

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