Reported by Nikolaus Schaller, Aug 24, 2011
Problem: default USB supply current is in the 60-70 mA range. As soon as MLO and/or U-Boot are loaded, the system draws more current and therefore the supply breaks down. A potential fix could be to add code to MLO/XLO to initialize the USB power controller to provide more current (e.g. 200-300 mA). This allows the device to boot and finalize further initialization. If this approach works is unclear. Reasons for doubt: * MLO code may draw more than 50 mA * other components may start up and draw additional current (display, backlight, UMTS module) * bulk capacitor has 100-200 uF but this may not be enough to stabilize the VBATT while the power controller is being reprogrammed
Comment 1 by Nikolaus Schaller, Nov 29, 2011
Well, in many practical cases it works. Nevertheless, I have seen in the git logs of the OpenPandora X-Loader that it also does something to enable early USB charging.
Comment 2 by Nikolaus Schaller, May 13, 2014
For the records, there is a disabled patch in our source: http://git.goldelico.com/?p=gta04-xloader.git;a=blob;f=board/omap3530 gta04/omap3530gta04.c;h=1d490c94ad11f5fdba1b3660cce340bde7fb6fa2;hb=H EAD#l112
Comment 3 by Nikolaus Schaller, Mar 19, 2015
For the OpenPandora charger patch compare: http://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-x-loader.git; a=commitdiff;h=b3646a83f9e67ec9a2de3182fd254557fd6ad9aa
Comment 4 by Nikolaus Schaller, Dec 18, 2017
Has been fixed by adding a "charge auto" command to U-Boot and execute it by boot.scr. Anyways, we don't have a separate X-Loader source tree any more. This is nowadays part of the U-Boot code and called "SPL".
Comment 5 by Nikolaus Schaller, Dec 18, 2017