Hi all.
This isn't really a question about uboot, more about the ixp425
We have an ixp425 product with a footprint for 2 SDRAM components. When we use 2 x IS42S16800 (8M x 16 x 4 banks) for a total of 32MByte everything works fine. But replacing these components with 2 x IS42S16400 (4M x 16 x 4 banks) for a total of 16MByte the board won't boot.
In both cases the PHYS_SDRAM_1_SIZE is set to 0x01000000 (16MByte) since the intent was always to use the smaller SDRAM configuration.
The SDRAM settings for the 32MB version are: #define CFG_SDR_CONFIG 0x18 #define CFG_SDR_MODE_CONFIG 0x01 #define CFG_SDRAM_REFRESH_CNT 0x400
And for the 16MB version: #define CFG_SDR_CONFIG 0x3A #define CFG_SDR_MODE_CONFIG 0x01 #define CFG_SDRAM_REFRESH_CNT 0x400
[ie the only change between the two configurations is the SDR_CONFIG value]
In particular the 64M enable (in SDR_CONFIG) is set for the 64MBit parts and the mem config field is set to %010 which is what the data sheet prescribes for two 4M x 16 parts.
The first version works fine (using 8Mx16x4 parts). The second version fails to boot with the appropriate components (-7 {143MHz} speed grade).
Has anyone used 64Mbit components with the ixp425 or similar? Can anyone comment on why the second configuration would fail?
Thanks
Jonathan Pratt ELPRO Technologies Pty Ltd