Messages in this thread | | | Date | Thu, 3 Jun 2010 14:23:09 +0200 | From | Daniel Mack <> | Subject | Re: [PATCH] usb-serial/ftdi_sio: fix DTR/RTS line modes |
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On Thu, Jun 03, 2010 at 12:32:25PM +0100, Alan Cox wrote: > On Thu, 3 Jun 2010 13:55:02 +0200 > Daniel Mack <daniel@caiaq.de> wrote: > > > Call set_mctrl() and clear_mctrl() according to the flow control mode > > selected. This makes serial communication for FT232 connected devices > > work when CRTSCTS is not set. > > > > This fixes a regression introduced by 4175f3e31 ("tty_port: If we are > > opened non blocking we still need to raise the carrier"). This patch > > calls the low-level driver's dtr_rts() function which consequently > > sets TIOCM_DTR | TIOCM_RTS. A later call to set_termios() without > > CRTSCTS in cflags, however, does not reset these bits, and so data is > > not actually sent out on the serial wire. > > If you've got hardware the other end expecting RTS/CTS signals you > really ought to set CRTSCTS.
I know. It is, however, a regression in my case, and there might be other cases where RTS/CTS aren't connected at all. The core of the problem is that the driver sets hardware flow control, even though the userspace asked for not doing that.
> However you patch makes complete sense in > terms of which way it is best to end up.
And it shouldn't break anything I'd say.
Thanks, Daniel
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