[LinuxBIOS] How to parameterise SDRAM init on Geode GX1?
juergen127 at kreuzholzen.de
Thu May 10 09:47:59 CEST 2007
the routine sdram_init() in LinuxBIOSv2/src/northbridge/amd/gx1/raminit.c does
a very slow SDRAM timing setup. On a 266MHz CPU the SDRAM will run at 76MHz
with a CAS latency of 3. You can't run a SXGA reolution with 64k colours on
such a slow system. On my mainboard I can't read the EEPROM on the SODIMM, as
I have no schematics and do not know if the manufacturer has routed some of
the GPIOs as a I2C bus to this EEPROM. But I know the SDRAM chips on the
SODIMM in my system!
Is there a "regular" way in LinuxBIOS to parameterise the SDRAM setup with
some predefined macros in a (maybe) headerfile, so each GX1 based mainboard
could overwrite the slowest timing with its own faster timing (if the
programmer knows his SDRAM timings). In my case I can run some of my SODIMMs
at 120MHz at CL2, some other with 100MHz at CL2 (300MHz Geode GX1).
Maybe the trick with a searchpath for headerfiles. There will be a generic
file with the slowest timing in a directory at the end of the searchpath and
the prgrammer can provide his own timing headerfile that would be found first
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