I'm and Android guy, so I'm plenty familiar with how "firmware" works. However, when it comes to the Pi3, it seems to get hazy.
For example, on a cell phone, there are is a bootloader partition, which is upgradable through software flashing. The "firmware" resides on the /system partition (also upgradable, obviously).
Does the Pi3 have such a thing as a "bootloader" or other "microcode"-style upgradable "firmware"? Or when you say "firmware" are you referring to ANY data that resides on the microSD card?
If it's all on the microSD card, that means that the Pi itself does NOT actually have ANY upgradable firmware onboard. If you're upgrading what's on the SD card, that's only the kernel and such.
That means there is no actual upgradable chip on the Pi that can be flashed, that would contain improvements to onboard controllers, bootcode, or anything else.
Some clarity here would be nice.