On Wednesday, May 21, 2014 at 04:01:55 AM, Peter Schumann wrote:
This patch makes it possible to boot from battery on olinuxino Boards from Olimex.
We should not set DOUBLE_FETS in HW_POWER_MINPWR
Please explain how you arrived to this conclusion.
, it makes my system reset with in seconds while running on battery power.
Also mxs_power_enable_4p2() should not be called if running from battery. It switches VDDD and VDDA to LinReg mode and than turns off the VDDIO DCDC supply. At this point the system resets.
This has been tested on i.MX28 , can you please check what the differences are between these two chips and why it works only on one of them ?
If we run on battery this is no good idea because the LinRegs are chained behind VDDIO and battery voltage seems not enough to power the system from LinRegs. Also is the power system already running on DCDC after BootROM hands over to u-boot, so no sense in switching back to LinRegs.
The BootROM never hands over to U-Boot, so this really makes no sense. Can you please explain ? The BootROM handles over to U-Boot SPL, which configures the power block.
Also, I find it a very bad idea to depend on the BootROM to actually start the DCDC converter. I don't think we can universally say the DCDC converter is running when entering U-Boot SPL. I also don't think we can even depend on the power block configuration when exiting the BootROM -- for example in JTAG Boot Mode, the BootROM halts early in the boot process and will likely not configure anything with regards to the power block.
[...]
THanks!
Best regards, Marek Vasut