On 03/26/2016 09:56 AM, Iain Paton wrote: > Having reread the A20 datasheet yesterday, something in the back of my > mind was bothering me overnight so I took some time to check this morning. > > On the lime2 schematic we see the pins labeled as follows: > > F19 : VCC_CSI0 > E18 : VCC_CSI1 > > However the A20 datasheet doesn't label them this way, instead using: > > F19 : VCC-PE : Port E Power Supply > E18 : VCC-PG : Port G Power Supply > > no mention at all of CSI. CSI just happens to be a function that can be > multiplexed onto ports E & G. > > So lets assume for a moment we don't have a CSI device, or a CSI driver > and are not using those pins for CSI functions but are instead using > their default GPIO purpose, or in the case of PG perhaps for UART3 > or UART4. > > What happens when you disable the regulator? Hopefully from the above > you'll already have worked out that you lose ports E & G when you turn > their I/O power supply off and anything multiplexed onto those ports > becomes unuseable. >
Hi Iain, I took some time to go through the data sheets and your analysis is on point. I did raise an issue with Olimex via github . Maybe they will update their schematics. I do have my breakout board connected to GPIO-1.. and it turns out that mostly port G is exposed on GPIO-1. I'll be reverting Hans' patch locally so I can toggle some pins today. I am sure he will contribute his own thoughts on the matter. > I've also just tested building u-boot with LDO3 & 4 voltages set to > 3.3v to be the same as CubieBoard, this works for lime2. > So it's unlikely that the 2.8v & 2.3v settings from my previous patch > make sense. The crash is actually being caused by something else, > probably sequencing, due to unnecessarily turning the regulators off. > Whatever the reason, we don't have enough information in the > datasheets to know for sure so we simply shouldn't turn them off to > begin with. I just tried that on linux and axp20x-regulator.ko refuses to set the voltage on ldo4: [ 88.914653] at24 1-0050: 2048 byte 24c16 EEPROM, writable, 16 bytes/write [ 96.893312] axp20x-i2c 0-0034: AXP20x variant AXP209 found [ 96.910631] axp20x-i2c 0-0034: AXP20X driver loaded [ 96.955579] input: axp20x-pek as /devices/platform/soc@01c00000/1c2ac00.i2c/i2c-0/0-0034/axp20x-pek/input/input0 [ 96.971734] ldo4: failed to apply 3300000uV constraint(-22) [ 96.990646] axp20x-regulator axp20x-regulator: Failed to register ldo4 [ 97.012686] axp20x-regulator: probe of axp20x-regulator failed with error -22 Perhaps this requires another patch , but unless there's a real need for me to verify this, I'll simply revert the u-boot patch and enjoy working GPIO. Michael  https://github.com/OLIMEX/OLINUXINO/issues/35  https://www.spinics.net/lists/devicetree/msg118871.html -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.