[U-Boot-Users] SDRAM on ixp425
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
Jonathan,
On 9/7/07, Jonathan Pratt Jonathan.Pratt@elprotech.com wrote:
Hi all.
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.
... The first version works fine (using 8Mx16x4 parts). The second version fails to boot with the appropriate components (-7 {143MHz} speed grade).
Both are -7 parts? And, please mention the product code on the IXP. Is it a B-0 or B-1 stepping? There were some issues with some speed parts, the main reason for the B-1 stepping.
Here are some notes I can access now:
* PRIXP420BD - Intel IXP420 B-0 stepping, 533 MHz, lead-free * PRIXP420ABD - Intel IXP420 B-1 stepping, 533 MHz, lead-free o For the B-1 stepping the SDRAMs must have a minimum refresh cycle time (tRC or tRFC) of 67.5 ns or less. The Intel software must be modified as per page 47 of Software Specification Update. o The two 32-bit -7 parts currently selected (Micron and ISSI) do not fulfill this requirement. Either a faster part, or two 16-bit parts in parallel are required. + No faster parts are available, or hardly available. Two 16-bit parts in parallel are required.
I think the 16-bit parts have -6 speed grade, which is why they work. I can look into our design notes next week.
Regards,
Leon.
Hi Leon.
The processors parts are B1 stepping (ABB - running at 266MHz). Both SDRAM parts are -7.
Interestingly, if I use the uboot version for the 128Mbit parts on the boards populated with the 64Mbit parts (ie CFG_SDR_CONFIG set to 0x18) then uboot will boot (looking for all the world as though it is configured correctly). However, with an incorrect SDRAM configuration, there are holes in the RAM memory and memory checks fail.
Therefore the SDRAM timing seems to be OK. The configuration for 64MBit parts is what seems to be killing the system.
Jonathan Pratt ELPRO Technologies Pty Ltd
-----Original Message----- From: Leon Woestenberg [mailto:leon.woestenberg@gmail.com] Sent: Friday, 7 September 2007 9:29 PM To: Jonathan Pratt Cc: u-boot-users@lists.sourceforge.net Subject: Re: [U-Boot-Users] SDRAM on ixp425
Jonathan,
On 9/7/07, Jonathan Pratt Jonathan.Pratt@elprotech.com wrote:
Hi all.
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.
... The first version works fine (using 8Mx16x4 parts). The second version
fails to boot with the appropriate components (-7 {143MHz} speed
grade).
Both are -7 parts? And, please mention the product code on the IXP. Is it a B-0 or B-1 stepping? There were some issues with some speed parts, the main reason for the B-1 stepping.
Here are some notes I can access now:
* PRIXP420BD - Intel IXP420 B-0 stepping, 533 MHz, lead-free * PRIXP420ABD - Intel IXP420 B-1 stepping, 533 MHz, lead-free o For the B-1 stepping the SDRAMs must have a minimum refresh cycle time (tRC or tRFC) of 67.5 ns or less. The Intel software must be modified as per page 47 of Software Specification Update. o The two 32-bit -7 parts currently selected (Micron and ISSI) do not fulfill this requirement. Either a faster part, or two 16-bit parts in parallel are required. + No faster parts are available, or hardly available. Two 16-bit parts in parallel are required.
I think the 16-bit parts have -6 speed grade, which is why they work. I can look into our design notes next week.
Regards,
Leon.
participants (2)
-
Jonathan Pratt -
Leon Woestenberg