Re: [RFC] USB driver for talking to the Microchip PIC18 boot loader

[mgross <640e9920@gmail.com>]

On Sat, Dec 29, 2007 at 05:15:30PM -0500, Alan Stern wrote:
> On Sat, 29 Dec 2007, mgross wrote:
> 
> > I'm playing around with a PIC based project at home (not an Intel
> > activity) and found I needed a usb driver to talk to the boot loader
> > so I can program my USB Bitwhacker with new custom firmware.  The
> > following adds the pic18bl driver to the kernel.  Its pretty simple
> > and is somewhat based on bits of a libusb driver that does some of
> > what this driver does.
> > 
> > What do you think?
> 
> Not to detract from your driver, but would it be possible to do the 
> whole thing in userspace using libusb?  Maybe by extending the driver 
> you mentioned?
>
Yeah, it has been done from user space using a libusb based
application.  (that didn't work with a usb-hub in the loop) and had
code that was just too nasty for words, so I made a kernel driver that
looks nicer to me and enables a nice python FW loader program to work.

What is the linux-usb policies on new drivers that could be
implemented in user space?  When does a kernel driver make  sense over
a libusb one?

--mgross