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OMAP 3730 200 MHz SDRAM config

DISCUSSION Orjan Friberg 1 participant 2 messages Mar 7, 2011 1 message not in the archive

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Orjan Friberg

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Hi,

I'm looking at configuring an OMAP 3730 board for 200 MHz SDRAM.

I've been looking at the kernel code (arch/arm/mach-omap2) the last
couple of days to try and figure out what I need to do. We're basing ourselves off of the Beagleboard, so I tried copying the 200 MHz Hynix SDRAM entry for Beagleboard-xM but that didn't help: it still (re)programs the SDRC clock to 166 MHz.

* Does the kernel at all use or depend on the boot loader's SDRAM config? (I'm using u-boot with a prepended configuration header.)

* Does the SDRAM setup/clocking depend on the MPU rate at all? I.e. do I need to boot Linux in 1 GHz to be able to set 200 MHz SDRC clock?

The clock config is a bit convoluted, so I'd appreciate any help.

Thanks,
Orjan

Appendix:

I'm using a program (user-mode app) called 'bandwidth' (which has an ARM port):
http://home.comcast.net/~fbui/bandwidth.html for measurements.

With big (several MB) sequential writes I get ~1170 MB/s. The theoretical max for a 166 MHz is 166*2 * 4 bytes = 1328 MB/s, so we're almost at 90%. We're not the only process accessing memory, and maybe there's some loss due to SDRAM refresh etc.

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Orjan Friberg
FlatFrog Laboratories AB
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Quoted 3 lines · Elvis Dowson

You probably need update x-loader. Try using the beagleboard x-loader project located at gitorious (v1.44) or the ti arago one (1.48, but not quite the latest in terms of support for beagleboard xm parts).

Looking at board/omap3530beagle/omap3530beagle.c for the memory part definitions. For the XM, the Numonyx part is at 165Mhz, and the Micron part is at 200Mhz.

I'm using u-boot with a configuration header, and there I have set the new CTRLA, CTRLB and RFR values (and I did compare the values with the Micron data sheet; apart from the TCKE value they are all identical).

But are you saying that the values set by the boot loader are preserved by the kernel? (In that case I wonder what the sdram-micron header file is for :)

Thanks,
Orjan

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Orjan Friberg
FlatFrog Laboratories AB