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

[Samuel Thibault]

Hello,

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.

Samuel

patch-qemu-usb-serial
Description: Text document