[U-Boot] Question about iMX28 SPI flash driver

Hello,

I've got an iMX28EVK board, added Winbond 25q64 flash and use the latest u-boot-imx version. For building u-boot I use the m28evk_config and set the the flash to winbond. It boots successfully through SD card and it also probes/recognize the SPI flash. Also the u-boot binary writes successfully through "sf write" to the flash(no error message).

The problem is, when reading the SPI flash through "sf read"; there are only "0".

Does anybody have an idea?

Thanks in advance.