[ELDK] R: R: Resource temporarily unavailable

Luigi Rizzi rizzi at algorab.com
Fri Nov 12 17:55:59 CET 2010

Hi Stefano,
a problem on the handshake line CTS is what I thought at first. I recompiled
the kernel setting NONE on every signal (RTS,CTS,CD,DTR) but nothing has
changed: everything works properly only on the STK board.

I check lots of times.. but it looks like there are no differences between
my carrier board and STK board, regarding these serial line signals. 

By the way, I noticed that with parameter "Number of TX DB for SCC2" set to
4, I get no error response for the first four write call: 

# ./test /dev/ttyS1

serial_tx: Resource temporarily unavailable
serial_tx: Resource temporarily unavailable

There's in your opinion something else I can check?

Best regards,

-----Messaggio originale-----
Da: Stefano Babic [mailto:sbabic at denx.de] 
Inviato: giovedì 11 novembre 2010 19.43
A: Luigi Rizzi
Cc: 'Wolfgang Denk'; eldk at lists.denx.de
Oggetto: Re: [ELDK] R: Resource temporarily unavailable

On 11/11/2010 06:23 PM, Luigi Rizzi wrote:
> Dear Wolfgang,
> on the original STK board SSC2 is used for the communication with the
> Ethernet Interface, so signals TXD2,RXD2,RTS2,CTS2,CS are connected to
> LXT905LE. 
> On my carrier board I connected TXD2, RXD2 and RTSD2 to the RS485 driver,
> and leave unconnected the others. 

If you use RTSD2, you should also use CTS, or at least do not program
the SCC to use handshaking. Check if CONFIG_PORT_RTS2_NONE is set, and
disable all control signals in your kernel configuration. The SCC waits
for the CTS line cleared by the modem, and it does not try to send
character if it does not see the answer from modem.

> The version I'm using is the one supplied by the module constructor (TQ)
> actually I don’t know how long it should take to jump at these new
> versions...

This is a difficult question...it depends on a lot of factors, from your
level of expertise, and if the board is supported by recent kernels, and
what you did on 2.4 kernel to allow the kernel to boot. However, TQ
modules are supported in 2.6.x kernel.

Best regards,
Stefano Babic

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