Thanks for your help.
I finally found why my SDRAMs weren't working properly. My DSP was beeing reset
by the supervisor chip when accessing the SDRAMs. So CCS was loosing
communication with my DSP.
The supervisor chip control the 5V, 3.3V & 1.8 V on the board. When accessing
the SDRAM, the 5V contains some glitch +/- 300mV. This chip detect it as power
loss, reseting then the DSP.
The initial mistake was to place this chip to close to the DSP & SDRAM, while on
the DSK it is closer the power supply.