[U-Boot-Users] cache and buffer problems

Hi, I got a problem about cache and write buffer after I download the u-boot.bin to my board (s3c4510),I found that I can't erase the Flash (at49bv1614) any more ,so the u-boot is still running on my board I can't erase it . First I think it is caused by the Flash sector locked , but I check the status by software , it shows that it isn't be locked . So I think about write buffer and cache ,maybe my erase command cannot arrive flash,but in write buffer. from the datasheet ,it seems that s3c4510 can't close the cache while it is working untill system reset and clear the cache enable bit in SYSCFG register . but after reset ,u-boot enable cache again . plz tell me how to erase the flash or disable the cache. thx!