you have to do it via your bootloader (u-boot) which sets up
the DDR memory controller.
Linux (already) assumes memory is available.
Are you sure linux kernel is changing DDR_SDRAM_CFG ?
When our linux-2.6.28 kernel is up, it's still 0xc3080000 when I read
physical address 0xe0002110.
Btw. We did some performance tests with 16 bit bus-width (DDR2 memory)
and surprisingly performance was almost as good as 32 bit bus-width
---
N. van Bolhuis.
Frank Prepelica wrote:
Hi all,
Does anyone knows how to set the DDR data bus width to 16Bit in linux?
I've found that
option in U-Boot in the MPC8313ERDB_config file. (verfied with a memory
dump of the
CPU register (DDR_SDRAM_CFG) - the 16Bit DBW is set(10b) ). But after
starting
linux the value is set to 00b (=reseverd).
We are using a customized MPC8313ERDB board.
Thanks in advance
Kind regards
Frank Prepelica
Software Design Engineer
Ubidyne GmbH
Lise-Meitner-Str.-14
89081 Ulm - Germany
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