Re: USB serial support / Prolific PL2303 Driver

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Apr 08, 2013 at 07:35:49PM +0200, Hans Beckerus wrote:
> >USB starts as one of the last things in the kernel boot process, so the
> >best you can ever get is a summary of what happened during the boot, not
> >the kernel boot messages as they happen because they happen before the
> >USB device is initialized.
> Sure. That is an acceptable limitation. However, I wonder if this
> will be different once we get U-Boot USB console support on this
> platform?
> Question though is if Linux  ever will be able to benefit from a
> first stage driver already being kicked-off by U-Boot.

For USB, no, that can't really happen, as the whole USB stack has to be
started up "from scratch" after u-boot starts Linux up.  There's no way
that Linux can take a "already discovered" usb stack and continue it's
usage.

Unless you possibly use Linux for your bootloader, and if so, in that
case, you don't need u-boot, and only do all device discovery once,
which is the ideal thing from a speed standpoint.

Good luck,

greg k-h