Hi Oliver,
On Wed, Mar 01, 2017 at 01:52:16PM +0100, Olliver Schinagl wrote:
Hi list,
When powering up an AXP209, the default value for LDO3 output is enabled. This works fine. However if for whatever reason, LDO3 is disabled, for example by OS during reboot and u-boot enables LDO3 again, the PMIC shutsdown (without setting an interrupt) causing the board to hang. This behavior has been seen from Linux as well, u-boot disables LDO3 as a default value, the kernel enables it per its DTS, the kernel hangs as the PMIC gets shut down.
The root cause is that some boards have to high capacitance on the LDO3 output port causing inrush currents exceeding the maximum of the AXP209.
The fix is to turn on the LDO3 at the lowest possible voltage and then set the final voltage.
If the capacitance is really big (due to a connected device for example) the AXP209 also features VRC, or Voltage Rate Control, which allows the voltage ramp up to be even slower.
This patch series implements the above with a few tiny, cleanups I ran into underway.
The initial discussion with some scope screenshots can be found in the linux-sunxi mailing list [0].
If you don't CC the proper maintainers, no one is going to pick the patches.
Maxime