[U-Boot-Users] ECC DIMM's with walnut board

[U-Boot-Users] ECC DIMM's with walnut board

[Thomas Schäfer]

Hi all,

I compiled u-boot 0.3.0 for the walnut board and run it, it was working fine. Then I replaced the shipped 32MB DIMM module with a 256MB DIMM module with ECC and the board hang:

U-Boot 0.3.0 (Apr 25 2003 - 12:10:17)

CPU:   IBM PowerPC 405GP Rev. E at 200 MHz (PLB=100, OPB=50, EBC=50 MHz)
           PCI sync clock at 33 MHz, internal PCI arbiter enabled
           16 kB I-Cache 8 kB D-Cache
Board: WALNUT405-EVB_22
I2C:   ready
DRAM:  256 MB
***hang***

I examined the function spd_sdram in cpu/ppc4xx/spd_sdram.c and found that the ECC Correction Enable bits in the SDRAM0_ECCCFG register are set to 1 when ECC DIMM is detected. I removed this setting and the board was working without any problems.
The 405GP Reference board manual says that using an ECC DIMM on a walnut board, only half of the total DIMM size is available if it is enabled for ECC, but this seems not to work on my board.

Has anyone tried out to run the walnut board with ECC DIMM's? What DIMM's did you use? The DIMM I was trying is Infineon HYS72V32220GU (256MB, PC133-222-520).

Best regards

Thomas Sch?fer

____________________________________

GIGA STREAM - UMTS Technologies GmbH

Konrad-Zuse-Str. 7
66115 Saarbr?cken

Tel.: + 49 (0)681 / 95916 - 203
Fax:  + 49 (0)681 / 95916 - 100
E-mail: tschaefer at giga-stream.de

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[U-Boot-Users] ECC DIMM's with walnut board

[Thomas Schäfer]

Hi all,

I tried to boot a walnut board with a 256 ECC DIMM using u-boot 0.3.0, but
didn't succeed. When examining the code in the function spd_sdram in
cpu/ppc4xx/spd_sdram, I found that the ECC configuration code is probably
wrong. I suppose, that the following lines

	/* now check for ECC ability of module. We only support ECC
	 *   on 32 bit wide devices with 8 bit ECC.
	 */
	if ( (read_spd(11)==2) && ((read_spd(6)==40) || (read_spd(14)==8)) ){
	   sdram0_ecccfg=0xf<<SDRAM0_ECCCFG_SHIFT;
	   ecc_on = 1;

should be replaced with

	/* now check for ECC ability of module. We only support ECC
	 *   on 32 bit wide devices with 8 bit ECC.
	 */
==>	if ( (read_spd(11)==2) && ((read_spd(6)==40) &&
read_spd(14)==8)) ){ <==
	   sdram0_ecccfg=0xf<<SDRAM0_ECCCFG_SHIFT;
	   ecc_on = 1;

The reason is, that the if statement in the first code is also true for 72
bit ECC devices. So ECC is enabled for such a device which fails in the
following. The changed code works for me with several DIMM types (32MB
without ECC, 256 MB with ECC and without ECC), but I'm not an expert with
all types of SDRAM and so I'm not sure if I fully understood the code in
that place. Any ideas, comments?

Best regards


Thomas Sch?fer

____________________________________

GIGA STREAM - UMTS Technologies GmbH

Konrad-Zuse-Str. 7
66115 Saarbr?cken

Tel.: + 49 (0)681 / 95916 - 203
Fax:  + 49 (0)681 / 95916 - 100
E-mail: tschaefer@giga-stream.de

[U-Boot-Users] ECC DIMM's with walnut board

[Kenneth Johansson]

On Mon, 2003-04-28 at 16:07, Thomas Sch?fer wrote:
> Hi all,

> following. The changed code works for me with several DIMM types (32MB
> without ECC, 256 MB with ECC and without ECC), but I'm not an expert with
> all types of SDRAM and so I'm not sure if I fully understood the code in
> that place. Any ideas, comments?
> 
> Best regards
> 
> 
> Thomas Sch?fer
> 

This clearly changes nothing for non ECC dimms and you are the first I
heard of using ecc so you are probably right :)  

Do a proper patch and send it over to Wolfgang. You could take out a few
more parentheses 


-- 
Kenneth Johansson	
Ericsson AB                       Tel: +46 8 719 70 20
Tellusborgsv?gen  90              Fax: +46 8 719 29 45
126 25 Stockholm                  ken at switchboard.ericsson.se

[U-Boot-Users] ECC DIMM's with walnut board

[Thomas Schäfer]

Wolfgang,

please find attached a patch for the cpu/ppc4xx/spd_sdram file. The ECC
configuration code in function spd_sdram is changed so that 72 bit ECC
DIMM's are used in non-ECC mode. Using those DIMM's in ECC mode doesn't work
on the walnut board. If working, it would make probably no sense, because
only the half of the DIMM size can be used in ECC mode.
CFG_MONITOR_LEN in include/configs/WALNUT405.h was changed to 256, because
192 was too small for the configuration provided with u-boot-0.3.0

Maybe the patch is of some use for the project.

Best regards,

Thomas Sch?fer

____________________________________

GIGA STREAM - UMTS Technologies GmbH

Konrad-Zuse-Str. 7
66115 Saarbr?cken

Tel.: + 49 (0)681 / 95916 - 203
Fax:  + 49 (0)681 / 95916 - 100
E-mail: tschaefer at giga-stream.de

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[U-Boot-Users] ECC DIMM's with walnut board

[Thomas Schäfer]

Kenneth,

what type of (32 bit wide device) SDRAM is the ECC configuration piece for?
As far as I understood the walnut manual, DIMM's are always designed as 64
bit devices (which can be used as 32 bit devices, but not in ECC mode).

Best regards,

Thomas Sch?fer

____________________________________

GIGA STREAM - UMTS Technologies GmbH

Konrad-Zuse-Str. 7
66115 Saarbr?cken

Tel.: + 49 (0)681 / 95916 - 203
Fax:  + 49 (0)681 / 95916 - 100
E-mail: tschaefer at giga-stream.de

[U-Boot-Users] ECC DIMM's with walnut board

[Wolfgang Denk]

Dear Thomas,

in message <FIEJJAKAABLMHFKFECNJGEAMGPAA.tschaefer@giga-stream.de> you wrote:
> 
> I tried to boot a walnut board with a 256 ECC DIMM using u-boot 0.3.0, bu=
> t
> didn't succeed. When examining the code in the function spd_sdram in
> cpu/ppc4xx/spd_sdram, I found that the ECC configuration code is probably
> wrong. I suppose, that the following lines

I was waiting for a regular patch, but obviously you won't send one.

So I added this now manually.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
Sorry, but my karma just ran over your dogma.