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Rtems_termios_ioctl problem



Thomas Doerfler wrote:
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>
> Hi,
>
> wow, big mistake, I have outed me to know about the flow control
> stuff...  :-)
>
> After digging around in the code (mainly in fillBufferQueue()), I have
> extracted the following lines, which are used there when the input
> buffer has enough space for further reception (which is definitively the
> case when the buffer was flushed).
>
>   
Should this code be moved to a helper subroutine that is invoked from 
both places?
> - ---- snip
> tty->flow_ctrl &= ~FL_IREQXOF;
> /* if tx stopped and XON should be sent... */
> if (((tty->flow_ctrl & (FL_MDXON | FL_ISNTXOF))
>      ==                (FL_MDXON | FL_ISNTXOF))
>       && ((tty->rawOutBufState == rob_idle)
> 	  || (tty->flow_ctrl & FL_OSTOP))) {
> 	    /* XON should be sent now... */
> 	    (*tty->device.write)(tty->minor,
> 		(void *)&(tty->termios.c_cc[VSTART]),
> 		1);
> 	  }
> 	  else if (tty->flow_ctrl & FL_MDRTS) {
> 	    tty->flow_ctrl &= ~FL_IRTSOFF;
> 	    /* activate RTS line */
> 	    if (tty->device.startRemoteTx != NULL) {
> 	      tty->device.startRemoteTx(tty->minor);
> 	    }
> 	  }
>
> - ---- snip
>
> Stephane, can you add this after you have flushed to input buffer? I
> checks, whether XON must be sent (and sends it possibly) and it also
> takes care about the HW flow control.
>
> wkr,
> Thomas.
>
>
> Eric Norum schrieb:
>   
>> Can someone who's familiar with the flow-control details of termios  
>> have a look at the interaction with this?
>>
>> Why do you need to send a break?   The 'correct' way to do this would  
>> involve changes to low level drivers.  A workaround, for those  
>> applications that really need to drive the serial line to such a  
>> state, is to temporarily set the serial line speed to a lower value,  
>> then transmit a NUL character, wait the the transmitter is again  
>> idle, and restore the line speed.  Of course this means that any  
>> incoming characters will be mangled during this time.....
>>
>> <Controversial>
>> My feeling is that the termios code is already too complicated and  
>> that all the code to support XON/XOFF flow control should be optional  
>> or removed.
>> Does anyone really use this antiquated and unreliable  means of flow  
>> control any more?
>> I'd be happy with leaving flow control up to the hardware (RTS/CTS)  
>> and dropping all references to flow control from the generic termios  
>> code.
>> /<Controversial>
>>
>> On May 2, 2007, at 10:53 AM, Arquer Stephane wrote:
>>
>>     
>>> Hi,
>>>
>>> Thanks for your answers, I've modified the file with your advices
>>>
>>> case TCFLSH:
>>> 	{
>>> 	switch (args->buffer) {
>>> 		case TCIFLUSH:	/* flush input buffer */
>>> 			{												
>>> 			if ( tty->rawInBuf.Tail != tty->rawInBuf.Head ) /* buffer is not  
>>> empty*/
>>> 				rtems_interrupt_disable (level);
>>> 				tty->rawInBuf.Head = tty->rawInBuf.Tail;
>>> 				rtems_interrupt_enable (level);
>>> 			}
>>> 			break;			
>>> 		case TCOFLUSH:	/* flush output buffer*/
>>> 			{
>>> 			if ( tty->rawOutBuf.Tail != tty->rawOutBuf.Head )/* buffer is  
>>> not empty*/
>>> 				rtems_interrupt_disable (level);
>>> 				tty->rawOutBuf.Head = tty->rawOutBuf.Tail;
>>> 				rtems_interrupt_enable (level);			
>>> 			}
>>> 			break;
>>> 				
>>> 		case TCIOFLUSH:	/* flush input & output buffer*/
>>> 			{
>>> 			if ( tty->rawInBuf.Tail != tty->rawInBuf.Head )
>>> 				rtems_interrupt_disable (level);
>>> 				tty->rawInBuf.Head = tty->rawInBuf.Tail;
>>> 				rtems_interrupt_enable (level);
>>> 						
>>> 			if ( tty->rawOutBuf.Tail != tty->rawOutBuf.Head )
>>> 				rtems_interrupt_disable (level);
>>> 				tty->rawOutBuf.Head = tty->rawOutBuf.Tail;
>>> 				rtems_interrupt_enable (level);	
>>> 			}
>>> 			break;
>>> 		}				
>>> 	}
>>> 	break;
>>>
>>> 	
>>> 	
>>> I call ioctl function with tcflush()
>>>
>>> int tcflush (int fd, int queue)
>>> {
>>> 	switch (queue){
>>> 		case TCIFLUSH:			
>>> 		case TCOFLUSH:
>>> 		case TCIOFLUSH:
>>> 			return ioctl(fd,TCFLSH,queue);
>>> 			break;
>>> 		default: return -1
>>> 		} //switch
>>> }
>>>
>>> And I am not sure that I'm using the handler ( args->buffer )in the  
>>> case TCFLSH correctly
>>>
>>> Another problem is for the TCSBRK case.
>>> Can you explain to me how can I send the break signal ?
>>>
>>> case TCSBRK:
>>> 	{
>>> 		??
>>> 	}
>>> 	break;	
>>>
>>>
>>> Thanks for your help.
>>>
>>> Stephane
>>>
>>>
>>>
>>>       
>>>> -----Message d'origine-----
>>>> De : Eric Norum [mailto:norume at aps.anl.gov]
>>>> Envoy? : mercredi 2 mai 2007 16:00
>>>> ? : Arquer Stephane
>>>> Cc : rtems-users at rtems.org
>>>> Objet : Re: Rtems_termios_ioctl problem
>>>>
>>>>
>>>> 1) Why place the NUL into the buffer?
>>>> 2) The raw input buffer is a ring buffer, so I don't think that your
>>>> rawnc calculation is right.
>>>> 3) The semaphore is being used for process synchronization, not for
>>>> mutual exclusion, so obtaining and releasing it like this is
>>>> incorrect.
>>>>
>>>>
>>>> It seems to me that all that's necessary is to:
>>>>          rtems_interrupt_disable (level);
>>>> 	tty->rawInBuf.Head = tty->rawInBuf.Tail;
>>>> 	rtems_interrupt_enable (level);
>>>>
>>>>
>>>> This will flush the 'raw' input buffer.  Should something happen to
>>>> the 'cooked' buffer as well?
>>>>         
>>> I don't use it for the moment.
>>>
>>>       
>>>> On May 2, 2007, at 7:28 AM, Arquer Stephane wrote.  The comment at
>>>> the top of rtems_termios_enqueue_raw_characters
>>>>
>>>>         
>>>>> Hi,
>>>>>
>>>>> As I wrote in my previous email, I'm still trying to modify the
>>>>> file termios.c to add TCFLSH request like following:
>>>>>
>>>>> case TCFLSH:
>>>>> 	{
>>>>> 	switch (args->buffer) {
>>>>> 		case TCIFLUSH:	/* flush input buffer */
>>>>> 			{
>>>>> 			unsigned int head;
>>>>> 			sc = rtems_semaphore_obtain
>>>>>           
>>>> (tty->rawInBuf.Semaphore,
>>>>         
>>>>> 								
>>>>>           
>>>> 	RTEMS_WAIT,
>>>>         
>>>>> 								
>>>>>           
>>>> 	RTEMS_NO_TIMEOUT);
>>>>         
>>>>> 								
>>>>> 			int rawnc = tty->rawInBuf.Tail -
>>>>>           
>>>> tty->rawInBuf.Head;
>>>>         
>>>>> 			if ( rawnc < 0 )
>>>>> 				/* buffer is not empty*/ 	
>>>>>           
>>>> 				
>>>>         
>>>>> 				head = tty->rawInBuf.Head;
>>>>> 				tty->rawInBuf.Tail = head;
>>>>> 				tty->rawInBuf.theBuf[head] = '\0';
>>>>> 					
>>>>> 			sc = rtems_semaphore_release
>>>>>           
>>>> (tty->rawInBuf.Semaphore);					
>>>>         
>>>>> 			}
>>>>> 			break;
>>>>>
>>>>> I don't know if it is the correct way to flush the buffer. If
>>>>> someone knows how to do it,I'm interested.
>>>>>
>>>>> Thanks for your help.
>>>>>
>>>>> St?phane.
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> rtems-users mailing list
>>>>> rtems-users at rtems.com
>>>>> http://rtems.rtems.org/mailman/listinfo/rtems-users
>>>>>           
>>>> -- 
>>>> Eric Norum <norume at aps.anl.gov>
>>>> Advanced Photon Source
>>>> Argonne National Laboratory
>>>> (630) 252-4793
>>>>
>>>>
>>>>
>>>>         
>
>
> - --
> - --------------------------------------------
> IMD Ingenieurbuero fuer Microcomputertechnik
> Thomas Doerfler           Herbststrasse 8
> D-82178 Puchheim          Germany
> email:    Thomas.Doerfler at imd-systems.de
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