tty/serial: Need clarification on Support for 4+M Baudrate

[Alan Cox]

On Thu, 12 Jan 2012 10:49:38 +0100
Rajanikanth H V <rajanikanth.hv at stericsson.com> wrote:

> Alan,
> 
> Thanks for your response, suggested modification helped to get 4.8M baud
> but not 4.05M as this is being approximated to 4.0M baud which happens in
> tty_termios_encode_baud_rate(...).

Only if you don't have the BOTHER flag set and only for returned data to
user space.

When you do a TCSETS2 ioctl and have BOTHER set as the rate as well as a
c_ispeed/c_ospeed the exactly value is given to the driver.

Alan