[Nexus 5 Original Android Development] show-p1984:
There will be no fast charge. It is dangerous for a bunch of reasons, the main one being:

Assume you have a poorly built motherboard, an ASROCK, or GIGABYTE, or (god beware) a FOXCONN (I wouldn't trust those things as far as I can throw them, but hey, it's your pc...). Those, and others, usually are lacking safety features of the USB ports. Why? Money. What features? Overload protection.

A USB 2.0+ port can only deliver up to 500mA, USB 3.0 only 1A. If your phone is now hacked to draw 1200mA++ from an USB2 port without that protection there are three things that could happen:

1) your USB Controller on your board fries, or rather it's power supply. So no USB on that board anymore.

2) your board fries.

3) A combination of 1) or/and 2) + your phone fries because something happened on your board and it now delivers 12V+ over USB. (unlikely, but it has happened)

I am speaking with experience here. I am etching my own µC boards, and during etching there might always be some part not fully cleared. So you have two options: a) Let out that crazy scientist and look over that board for 4-48hours (depending on it's complexity) or b) just hook it up and test it. Let's guess what I do? Right. The faster one. b.

When I started I used to use my old PC in the basement as USB power supply and flash machine. It was an 8 year old machine, a 1333Mhz AMD Athlon on an old foxconn board. (yeah, I know... Now...)

Let's just say that, one evening, the PC didn't survive the testing. The first board with a short circuit left over from etching killed the USB on the mainboard. But now comes the awesome part: Something went so horribly wrong on that board that USB now delivered full 13.4Volts, which essentially killed all peripherals connected to it.

From there on I used an externally powered cheap 5 bucks USB hub. Lesson learned.

That short circuit pulled 900mA from the USB port. You phone can easily draw 1200mA + losses.

USB3 is usually fine with a small overload, but with an exception: It cannot last for too long.

USB3 is designed to run HDDs without external power, and since all HDDs are basically big electronic motors, they will pull more current in the first few seconds of the spin up. As said earlier: USB3 can handle that, for a short period. But running something that is specifically designed to support PEAK load for a short time under that peak load permanently isn't a good idea.

Long story short: No fastcharge. Same as I won't allow 1.6V voltages for the soc. It's madness. Granted, those cases may only apply to 2% of the people ever going to use my kernel, but just because it's very unlikely that you use the airbags in your car doesn't mean that we can just sell them for spare parts and gas money.

KControl is in no way an exclusive app that has some black magic in it to control this kernel. It uses the sysfs exported functions by this kernel to do the work. All of it's functions can be performed on the shell as well, or by another well written app. It is meant to be a donation option for people and to give them something more back for their money. I just recommend it because I know that it works flawless. It gives you control over all cores of your device, where most apps still struggle. (in fact most apps only care about cpu0)