My board has P2020 with 1GByte discrete ddr3 (4 sdrams* 128Mx16). We now have 30 boards of which 3 show unstable behaviour: uboot ok but linux crashes due to kernel oops (bus-, paging-, segmentation- errors) indicating unstable instruction fetches from ddr3.
With Codewarrior-tap I ran DDRValidation tool on these 3 boards and all 3 are validated ok: ddr operational testing of full 1GByte does not show errors. However, running linux from ddr3 is unstable ?
P2020 DDR data rate = 666.66 Mbps (ddrclkin=66,666 Mhz*10) >> ddr_mck = 333.33 Mhz
On one board I changed this to 600 Mbps datarate (ddrclkin=100M*6) >> ddr_mck = 300 Mhz but stays unstable.
Could it be that some ddr3-sdram configuration parameter is causing trouble if fast consecutive burst accesses (linux, dual core) , while cw-tap-ddrv access is less stringent ?