using SCC4 on MPC8272ADS

Vitaly Bordug vbordug at
Wed Sep 21 21:40:21 EST 2005

Landau, Bracha wrote:
> I reconfigured the kernel so that only SCC1 and SCC4 are supported. The same thing happens as before.
> Another bit of info is that if I run with console=ttyCPM1 as a kernel command line parameter, so that u-boot outputs to one port and the kernel outputs to the other, if I type "ls > /dev/ttyCPM0" the system hangs.

Heh, didn't noticed, that you should use the latest rc of the linux 
kernel. I used to fix second UART in rc7 AFAIR.
> -----Original Message-----
> From: Vitaly Bordug [mailto:vbordug at]
> Sent: Wednesday, September 21, 2005 1:56 PM
> To: Landau, Bracha
> Cc: linuxppc-embedded at
> Subject: Re: using SCC4 on MPC8272ADS
> Landau, Bracha wrote:
>>I am using the MPC8272ADS with kernel 2.6.10. The kernel is configured to support 4 CPM SCCs, of which 1 and 4 are connected on the board.
>>I created device files as follows:
>>mknod /dev/ttyCPM0 c 204 46
>>mknod /dev/ttyCPM1 c 204 47
>>mknod /dev/ttyCPM2 c 204 48
>>mknod /dev/ttyCPM3 c 204 49
>>If I boot the kernel using console=ttyCPM3 I see that it uses SCC4. But when I boot with console=ttyCPM0 and write to the second port using a command like "echo hello > /dev/ttyCPM3" I don't see that anything is being outputted to the second console.
>>What am I doing wrong?
> Funny - you said that SCC 1 and 4 are connected to the board; than why 
> you are enabling SCC2 and SCC3?
> This board does have 2 SCCs assigned for UARTs. No need to configure 
> SCC2 and SCC3 - this is useless and may lead to kernel crash. This board 
> will use in the correct configuration /dev/ttyCPM0 <SCC1> and 
> /dev/ttyCPM1 <SCC4>.


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