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Date: Thu, 3 Jun 2010 14:23:09 +0200 From: Daniel Mack <daniel@...aq.de> To: Alan Cox <alan@...ux.intel.com> Cc: linux-kernel@...r.kernel.org, Greg Kroah-Hartman <gregkh@...e.de>, Johan Hovold <jhovold@...il.com>, linux-usb@...r.kernel.org Subject: Re: [PATCH] usb-serial/ftdi_sio: fix DTR/RTS line modes 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@...aq.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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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