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. I haven't checked other schematics, but all of the Olimex A10/A20 boards along with Cubieboard & CubieTruck label these pins as VCC_CSIn It would be my guess that there's a reference design being given to manufacturers, perhaps the original Cubieboard even, that makes this mistake and everyone else has blindly copied it. So, unless we want to lose access to 24 GPIO pins for no real reason I'd suggest that the u-boot patch is reverted and/or the dts is altered such that the gpio driver claims the regulators and prevents them being turned off. The u-boot commit message and reasoning given on list are trivially proved incorrect. Ports E & G are not CSI-only, losing all other functions on these ports is not acceptable. 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. The people behind this need to take responsibility and clean up their mess. Iain -- 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.