On Tue, Sep 17, 2013 at 08:59:24AM -0700, York Sun wrote: > Albert, > > Pardon me if this is a dumb question. I have been working on powerpc > platforms in the past. Now we (the developers I work with) are exploring > ARM cores. I am searching how memory is initialized and found different > solutions. Some platforms have memory ready before u-boot even starts, > some simply write to a set of registers. I understand many platforms > don't share the IP of DDR controller. I am wondering if there is generic > DDR driver used by many ARM platforms, like the one we have for > powerpc/mpc85xx SoCs.
Thinking back, as a rule of thumb, PowerPC has SPD I2C data available, usually. That's not the rule for ARM. One of a few choices happen: 1) ROM sets up DDR. 2) U-Boot/SPL sets up the DDR controller. The problem is that the DDR controller is usually vendor-specific. Perhaps the flip-side here is that there's not so much a generic DDR driver for mpc85xx but simply one vendor for mpc85xx. Taking arch/powerpc/cpu/mpc85xx/ddr-gen3.c as what you're talking about, arch/arm/cpu/armv7/omap-common/emif-common.c would be an ARM-world example (the 'EMIF' is found on a large variety of TI parts, not just "omap" ones). > > Regards, > > York > > _______________________________________________ > U-Boot mailing list > U-Boot@lists.denx.de > http://lists.denx.de/mailman/listinfo/u-boot -- Tom
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