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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
