Re: [Xenomai-help] problem with serial example

[Wolfgang Grandegger <wg@domain.hid>]

On 05/24/2010 09:32 AM, Everett Wang wrote:
> On Mon, May 24, 2010 at 7:36 AM, Everett Wang <everteq@domain.hid> wrote:
>> On Mon, May 24, 2010 at 12:28 AM, Wolfgang Grandegger <wg@domain.hid> wrote:
>>> On 05/23/2010 06:19 PM, Everett Wang wrote:
>>>> On Sun, May 23, 2010 at 11:46 PM, Wolfgang Grandegger <wg@domain.hid> wrote:
>>>
>>>>> There are other possibilities to interact with Linux, e.g. telnet,
>>>>> slogin or netcat. But it's always good to have a console.
>>>>>
>>>> I guess I need a USB to ethernet for these.
>>>
>>> Yes.
>>>
>>> ...
>>>>> All three uarts are occupied by Linux and you cannot use them as
>>>>> rtserial. First you need to release at least one of them. What Linux
>>>>> config do you use for your board?
>>>>
>>>> I didn't do any configuration. Do you mean to config these during kernel
>>>> configuration?
>>>
>>> Can you show us the .config of your kernel?
>>>
>>> Some more insights:
>>>
>>> I think the serial ports for the beagle boards are configured in:
>>>
>>> http://lxr.linux.no/#linux+v2.6.34/arch/arm/mach-omap2/serial.c
>>>
>>> Therein you find entries like:
>>>
>>> http://lxr.linux.no/#linux+v2.6.34/arch/arm/mach-omap2/serial.c#L82
>>>
>>> As you can see, a regshift of 2 is used, which is not yet supported by
>>> the 16550A RTDM driver. Should not be a big deal to add it, though.
>>> Also, as "baud_base" you should use OMAP24XX_BASE_BAUD.
>>>
>>> Wolfgang.
>>>
>>
>> Thanks for the suggestions. The .config file is attached. I will look at the
>> code you pointed to today to study the configuration of the serial port.
>>
>> Everett
>>
> 
> Hi Wolfgang,
> 
> I looked at the serial.c and function you pointed too. I have can't figure
> out how to modify it. Could you point me to the right direction to read so
> I can understand and eventually improve the serial for beagleboard? I thought
> I could limit the kernel to use only one of the uart (console) by
> changing function
>  __init omap_serial_init(void):
> 
>  void __init omap_serial_init(void)
> {
>         int i;
> 
> //        for (i = 0; i < ARRAY_SIZE(omap_uart); i++)
> //                omap_serial_init_port(i);
>       omap_serial_init_port(2);
> }
> 
> But the kernel hangs during booting after printing this message:
> 
> uncompressing Linux... done.
> 
> I guess it is not that simple to let kernel not to claim the uart0 and uart1.

Yes, unfortunately. I would try to comment out the uarts you want to
use for rtser in the following struct:

http://lxr.linux.no/#linux+v2.6.34/arch/arm/mach-omap2/serial.c#L562

Maybe the better option is to download setserial from

http://sourceforge.net/projects/setserial/files/setserial/2.17/setserial-2.17.tar.gz/download

and cross-compile it for your target. Then try:

# setserial /dev/ttyS2 uart none

Wolfgang.