2010-08-17 17:19:44 Low Performance with DDR memory
Dusko Cencan (GERMANY)
Message: 92523
Hello,
We have designed a custom board with the bf548 and 128MB DDR RAM. Acutally it is 2x64MB. All 128MB are recognized and the board is working just fine. It is clocked 525/131 Mhz. I wonder why our application runs at the same speed as on our previous bf527 board with 32MB and slower SDRAM. The Application is quite memory intensive, so I expected a significant performance boost. Our board ist similar to the EZKIT, except that it has a lot of peripherial interfaces. The DDR is the same, but the one with higher max. clock (200Mhz). The DDR chip is MT46V32M16BN-5B:F TR:
download.micron.com/pdf/datasheets/dram/ddr/512MBDDRx4x8x16.pdf
Uboot is configured with these settings:
CONFIG_CLKIN_HZ 25000000
CONFIG CLKIN_HALF 0
CONFIG_CLKIN_BYPASS 0
CONFIG_VCO_MULT 21
CONFIG_CCLK_DIV 1
CONFIG_SCLK_DIV 4
I wonder, if anyone has suggestions how to improve the DDR performance and what could be configured wrong in the kernel/uboot. Right now, the DDR is not working at its max. speed, but should be faster then SDRAM on bf527.
Thanks in advance.
Dusko Cencan
QuoteReplyEditDelete
2010-08-17 17:30:01 Re: Low Performance with DDR memory
Mike Frysinger (UNITED STATES)
Message: 92524
how did you calculate your ddr timings ? did you use the spreadsheet referenced in the wiki ?
ez.analog.com/docs/DOC-1441
QuoteReplyEditDelete
2010-08-18 05:43:56 Re: Low Performance with DDR memory
Dusko Cencan (GERMANY)
Message: 92547
Hi Mike,
No, I use the default values. I will check the excel timing table. I noticed that there is no register for the bf54x series in this document.
QuoteReplyEditDelete
2010-08-18 06:32:33 Re: Low Performance with DDR memory
Dusko Cencan (GERMANY)
Message: 92551
There is definitely no settings for the bf54x series mentioned in this document. I also think, this is for SD RAM only.
Do you know where I can find a similar document, targeting the bf54x series with DDR RAM?
QuoteReplyEditDelete
2010-08-18 06:43:37 Re: Low Performance with DDR memory
Michael Hennerich (GERMANY)
Message: 92552 ez.analog.com/docs/DOC-1441
This Excel file includes two worksheets one for SDRAM and one for DDR.
-Michael
QuoteReplyEditDelete
2010-08-18 07:03:34 Re: Low Performance with DDR memory
Dusko Cencan (GERMANY)
Message: 92553
Sorry, I missed the second sheet ;-) Thanks
QuoteReplyEditDelete
2010-08-18 13:37:30 Re: Low Performance with DDR memory
Dusko Cencan (GERMANY)
Message: 92560
OK, I played a bit with clocks and timings. The CCLK/SCLK of 525/131.25Mhz is replaced by 600/150Mhz.
The registers for the timings are:
ctl0=0x2E0F060D
ctl1=0x20026323
ctl2=0x00000031
dhrystone runs 15 % faster now. This is equivalent to the 15% clock increase of CCLK.
Strange thing is that the following settings run about 10% slower, but the timings should be faster.
ctl0=0x22ce87d0
ctl1=0x20026323
ctl2=0x00000031
QuoteReplyEditDelete
2010-08-18 16:08:33 Re: Low Performance with DDR memory
Michael Hennerich (GERMANY)
Message: 92565 In order to do real L3 memory benchmarks - you need to turn caches off!