[uClinux-dev] Coldfire serial port problems

Greg Ungerer gerg at snapgear.com
Mon Mar 24 19:07:53 EST 2003


Hi Jean, Peter,

Peter Vandenabeele wrote:
> We have a problem with the Coldfire serial port (RS485), using the 
> 2.4.20-uc0 kernel on a coldfire 5407:
> 
> Under heavy load (high traffic) at high baudrate (115.2kbps) the 
> 'read' from the application sometimes hangs until the tty timeout
> expires. After the timeout everything is ok.
> 
> Any idea on this ? I was thinking about an interrupt (on RX and TX) 
> problem.

My first thought would be too check what happens in
mcfserial.c if the flip buffer fills up. Maybe it
stalls, and for some reason doesn't start processing
RX data again once the buffer has been emptied.
Just a thought anyway...


> I have seen a changelog to 2.5.63 from 
> 'http://www.linuxhq.com/kernel/changelog/v2.5/63/', saying that:
> 
> 
>><gerg at snapgear.com>
>>      [PATCH] fix m68knommu/ColdFire serial port hang
>>  
>>     This patches fixes a serial port "hang" on the m68knommu ColdFire
>>      serial driver. It was erroneoulsy looking for a state bit that
>>      is never set.
> 
> 
> Could this fix our problem ? I will give it a try anyway.

No, this won't be it. This problem was specific to changes in
2.5 kernels. 2.4.x kernels won't have this problem.

Regards
Greg



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