[LinuxBIOS] E7501 SDRAM command bug?

Steven J. Magnani steve at digidescorp.com
Tue Jun 14 17:34:48 CEST 2005


The boundaries are configured during the "sdram_set_registers" phase of
setup, but (for E7501) the "sdram_set_spd_registers" phase overrides
those values before the RAM commands are sent in the "sdram_enable"
phase. There is evidence in the code that this was not always the case.

Steve

-----Original Message-----
From: Ronald G. Minnich [mailto:rminnich at lanl.gov] 
Sent: Tuesday, June 14, 2005 9:25 AM
To: Steven J. Magnani
Cc: linuxbios at openbios.org
Subject: Re: [LinuxBIOS] E7501 SDRAM command bug?


I would need to look at that code more, but what is typically done is
the 
boundary registers are programmed so that the ram "size" is 0x4000000
and 
all the commands for setup are sent to the ram. Once all the ram init is

done, then the actual row boundaries are set. 

We do it this way because it saves a lot of computation that is not
really 
needed. 

ron








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