Messages in this thread | | | Date | Fri, 20 Jun 2008 06:22:20 -0500 (CDT) | From | "R.L. Horn" <> | Subject | Re: 2.6.25.3: serial problem (minicom) |
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On Fri, 20 Jun 2008, Hans-Peter Jansen wrote:
> Alan, I got to test this by applying the changeset (Olivier, many thanks > for your valuable hint, I'm sure, I will reuse this knowledge soon), to > the otherwise unchanged kernel, but unfortunately, it doesn't solve my > issue. > > A different patch must have changed the behavior/state of some RS232 lines > in the 2.6.25 time frame,
There was a deliberate change in DTR behavior, though I'm not up on the details. If you have a copy of 2.6.25.something handy and want to check that that's the problem, you might look at drivers/serial/serial_core.c. Round about line 2160 (in uart_configure_port()), you'll see:
/* * Ensure that the modem control lines are de-activated. * keep the DTR setting that is set in uart_set_options() * We probably don't need a spinlock around this, but */ spin_lock_irqsave(&port->lock, flags); port->ops->set_mctrl(port, port->mctrl & TIOCM_DTR);
Change the last line to:
port->ops->set_mctrl(port, 0);
which reverts to 2.6.24 behavior.
If your problem isn't resolved here, please contact me off-list with some details about your receiver, ntpd version, etc. and I'll look into it further. I've been thinking about building a WWVB doodad, and a solution to this might save me some grief later on.
> As another data point: using a usb <-> rs232 converter, the dcf device > got back to life again. It still doesn't work in its entirety, but at > least, some data arrives in ntpd. Expected is something similar to: > -#--#-#####-###--D--S124--2-p------p-----21-4-24-----8-- (incomplete) > but it reads: > ###############RADMLS1248124P124812P1248121241248112481248P > thus, obviously it doesn't get any 0 values back (displayed as - above).
That looks like a hardware problem. Odds are, something here (and it could be the USB<->RS232 converter or the DCF receiver or both) either isn't up to RS-232 specs or the receiver is making unfounded assumptions about the DTE port. In particular, I'd want to know the mark/space voltages coming out of that USB thingy.
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