On Wed, Mar 11, 2009 at 10:06:11PM +0300, Valentine Barshak wrote: > Josh Boyer wrote: >> On Tue, Mar 10, 2009 at 10:50:13PM +0300, Valentine Barshak wrote: >>> I was just going to submit a patch for that too. >>> Indeed, the denali_fixup_memsize() miscalculated a couple of address >>> field widths. We were lucky to eventually get the right result, >>> because the effect of the first error was killed by the other one. >>> According to the AMCC 440EPX/GRX user manual, >>> the Chip Select width is always fixed at 1 bit no matter >>> what is actually read from register DDR_10. >>> The workaround is to use a predefined chipselect value for 440EPx/GRx. >>> Also, setting the REDUC bit (REDUC = 1) enables 32-bit data path. >>> If REDUC = 0, full data path of 64 bits is used. >>> >>> Signed-off-by: Valentine Barshak <vbars...@ru.mvista.com> >>> Signed-off-by: Mikhail Zolotaryov <le...@lebon.org.ua> >> >> I've been looking over this one a bit more. At the moment, I'm inclined >> to queue this up in my -next branch. I would like to see if Mikhail >> could test it though, and have Valentine answer the question in the hard >> wired part. > > I've been looking at the docs once again and actually I couldn't find an > explanation there. And I don't have that e-mail from AMCC support that > I got a while back regarding the issue anymore. > There might have been some misunderstanding. > The docs (PPC440EPX UM 19.2 Device Address Mapping) say that the chip > select field width is always fixed at one bit, but this doesn't actually > mean that there's always one chip select used. > The patch works fine on Sequoia and another Sequoia-like board with 1GB > RAM installed, but it might not work with 2GB RAM. I've tried to play > with DDR0_10 settings and Sequoia works fine regardless of what's > actually written to DDR0_10. > So, probably the best way would be to fix that in u-boot > amcc/sequoia/sdram.c by doing mtsdram(DDR0_10, 0x00000100); instead of > mtsdram(DDR0_10, 0x00000300); > Sorry, for confusion, but after reviewing the docs, I think that > only REDUC interpretation has to be fixed. The chips select part should > be fixed in u-boot sdram code for Sequoia as was originally proposed by > Mikhail.
Ok, so we're back to using Mikhail's original patch then? josh _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
