I misplaced my cell phone charger about 2 months ago and ever since, had been charging my cell phone with the micro USB cable connected to the laptop. So far, I have managed to charge the phone before it completely exhausted the power. Until yesterday. I thought it is just a matter of plugging in, the cable into the phone and connect the other end of the cable to the computer. The phone did start charging. But at some point, it got enough power to bootup and decided to automatically bootup. Once booted up, it shows up as a USB Mass Storage device. But before it enumerates, the phone powers off again. The issue is that, before enumeration, the host controller gives out only 100 mA of current. It can give out 500 mA, only after enumeration. The current was just not enough to keep it going and it kept on booting up and powering down again and again.
Finally I found a way to break the dead lock by rebooting the computer and stop the boot at GRUB prompt. Turned out that the BIOS configured the USB Host Controller to give out 500 mA and it quickly charged up, enough to enumerate, so that I could turn on the computer again.
Read more: Thoughts about programming
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