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QCVS-DDRV passed but Linux kernel crash ?

Question asked by Stefan Vranken on Sep 4, 2017
Latest reply on Dec 7, 2017 by Stefan Vranken


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 ?

Kind Regards