Dear Guowen SHAN, > > In message <cf7369060903290628p2768907p9a0c2e40c8986...@mail.gmail.com> > you wrote: > > > > I'm porting u-boot-1.3.1 to customer board, which includes MPC850 and > 32MB SDRAM. > > When I turned off icache, bus can work correctly under 25MHz/50MHz clock > frequence. > > Note that CPU is working under 50MHz. However, the board only can work > with bus > > frequence of 25MHz with enabled icache. If I tried to set bus frequence > to 50MHz with > > enabled icache, it will crash with MCE. > > Easy problem - actually FAQ: please see > http://www.denx.de/wiki/view/DULG/UBootCrashAfterRelocation
I don't understand it completely. 25MHz with enabled icache could use burst to fecth instructions from RAM, which should have proved the UPM words and initialization sequence was ok, right? > <http://www.denx.de/wiki/view/DULG/UBootCrashAfterRelocation> > > > I don't know why. Since it can work at 25MHz with enabled icache, the UPM > words seem > > ok. Thanks for your advices! > > Keep in mind that the UPM setup is only part of the required RAM > initialization sequence. Follow the instructions in the chip > manufacturer's manual to the letter. > > >
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