On Tue, 11 Dec 2018, Priit Laes wrote: > From: Olliver Schinagl <oliver@xxxxxxxxxxx> > > In the past, there have been words on various lists that if LDO3 is > disabled in u-boot, but enabled in the DTS, the axp209 driver would > fail to continue/hang. Several enable/disable patches have been > issues to devicetree's in both the kernel and u-boot to address > this issue. > > What really happened however, was that the AXP209 shuts down without > a notice and without setting an interrupt. This is caused when LDO3 > gets overloaded, for example with large capacitors on the LDO3 output. > > Normally, we would expect that AXP209 would source 200 mA as per > datasheet and set and trigger an interrupt when being overloaded. > For some reason however, this does not happen. > > As a work-around, implement software-based 'regulator-soft-start' > property for AXP209 LDO3 regulator, which is used to first bring up > the LDO3 to the lowest possible voltage and then enable the LDO. > > After that, we can set the requested voltage as usual. > > Combining this setting with the regulator-ramp-delay allows LDO3 to > come up slowly and staggered, potentially reducing overall inrush current. > > Signed-off-by: Olliver Schinagl <oliver@xxxxxxxxxxx> > Signed-off-by: Priit Laes <plaes@xxxxxxxxx> > --- > Documentation/devicetree/bindings/mfd/axp20x.txt | 3 +++ > 1 file changed, 3 insertions(+) For my own reference: Acked-for-MFD-by: Lee Jones <lee.jones@xxxxxxxxxx> -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
