CM-T43: Linux: Known Issues

RTC

RTC time and date is not maintained when unit is unplugged from power supply, even if an RTC backup battery is installed Workaround: Use the following U-Boot commands to enable battery supplied time keeping: pmic TPS65218_PMIC write 10 b1; pmic TPS65218_PMIC write 10 fe; pmic TPS65218_PMIC write 10 a3 This sets the FSEAL bit, which forces the power supply for the RTC to stay on when the system is in the OFF state. Once set it will stay set until the battery is removed or the above commands are run again. More information on this bit can be found in section 8.5.2 of the TPS65218 manual.

OPP

U-Boot versions 0.97 and below do not modify the PMIC voltages. The PMIC retains its settings between resets, and as a result if CM-T43 is switched to a low performance OPP (below 800 Mhz), on reset U-Boot will be using low performance voltage settings for a high performance CPU frequency and may not finish booting. Workaround: Switch to performance governor (default governor) before initiating resets.