[ts-7000] RTS and DTR polarity reversed on /dev/ttyAM0?

["genosensor" <>]

Hi,

I've been trying to interface a microcontroller to /dev/ttyAM0
that requires RTS be asserted from the host be output before it will
transmit.

RTS is asserted by the TS-7200 until /dev/ttyAM0 is opened.
Then it is immediately deasserted.

At least, that's what I observe.

After some head scratching, I was forced to conclude that 
RTS and DTR on port AM0 were being output with their polarities
reversed -- they are deasserted when that should be asserted 
and visa-versa.

I've attached a patch to fix this.
Has anyone else run into this problem?
I've seen some posts about trouble with pppd that might be
explained by having these lines inverted.

---------------------

cvs diff -u ep93xx_amba.c (in directory
/home/brent/linux/technologic/linux24/drivers/serial)
Index: ep93xx_amba.c
===================================================================
RCS file:
/home/cvs/linux/technologic/linux24/drivers/serial/ep93xx_amba.c,v
retrieving revision 1.1
diff -u -r1.1 ep93xx_amba.c
--- ep93xx_amba.c       24 Mar 2005 23:35:57 -0000      1.1
+++ ep93xx_amba.c       27 Mar 2005 06:13:58 -0000
@@ -523,20 +523,17 @@
 
 static void csambauart_set_mctrl(struct uart_port *port, unsigned int
mctrl)
 {
-       struct uart_amba_port *uap = (struct uart_amba_port *)port;
-       unsigned int ctrl = 0;
+    struct uart_amba_port *uap = (struct uart_amba_port *)port;
        
        /* If there's no RTS and DTR for this UART, do nothing here */
-       if(     (uap->rts_mask == 0) && (uap->dtr_mask == 0) )
-               return;
-  
-    if ((mctrl & TIOCM_RTS) == 0)
-               ctrl |= uap->rts_mask;
-       
-    if ((mctrl & TIOCM_DTR) == 0)
-               ctrl |= uap->dtr_mask;
-    
-       UART_PUT_MCR(ctrl, port);
+    if ( uap->rts_mask | uap->dtr_mask ) {  
+      unsigned int ctrl = 0;
+      if (mctrl & TIOCM_RTS)
+                 ctrl |= uap->rts_mask;
+      if (mctrl & TIOCM_DTR)
+                 ctrl |= uap->dtr_mask;
+      UART_PUT_MCR(ctrl, port);
+    }
 }
 
 static void csambauart_break_ctl(struct uart_port *port, int break_state)







 
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