My mcasp was configured as slave, i change the define AUDIO_FORMAT in the file /sound/soc/davinci-evm.c i replaced SND_SOC_DAIFMT_CBM_CFM (master config) by SND_SOC_CBS_CFS (slave) , this make the codec in slave and the mcasp in master mode, now i can see the output signal on the mcasp0 pins.
Thank you very much.