[Qemu-devel] Re: [PATCH] USB serial device

[Samuel Thibault]

Hello,

Samuel Thibault, le Sun 13 Jan 2008 01:55:56 +0000, a écrit :
> Samuel Thibault, le Fri 11 Jan 2008 11:09:23 +0000, a écrit :
> > Samuel Thibault, le Fri 11 Jan 2008 00:23:12 +0000, a écrit :
> > > I would like to implement support for braille devices, and for this I'd
> > > need to first implement a USB serial device (FTDI chip).  Has anybody
> > > worked on that already?
> > 
> > Ok, was easier than expected, Here is a patch. The serial support is
> > incomplete however because qemu still lacks support for flow control and
> > modem lines.
> > 
> > You will notice in tty_serial_init that I made the baud values more
> > relaxed. This is because with divisor/baud conversions, things never get
> > exact, so we need to be laxist with the value. For instance here with
> > FTDI, the base divisor is 48000000/2, so for 57600 bps the guest needs
> > to choose between divisors 416 and 417, which bring to either 57692bps
> > or 57553bps but not exactly 57600bps. It happens that Linux chooses
> > divisor 416, hence 57692bps. Of course, the higher the speed, the worse
> > things get. The 1.1 factor is the smallest factor I could find between
> > usual bps values, notably B110, B134 and B150.
> 
> Here is an updated version, that takes parameters, so as to be able to
> notably provide the product ID.

There was a small bug, here is a fixed version.
I also have a braille device emulation patch which now works, but it
probably needs a bit more polishing.

Samuel

patch-qemu-usb-serial
Description: Text document