[coreboot] Intel 8xx northbridge ram init is wrong
Joseph Smith
joe at settoplinux.org
Tue Jun 2 17:13:30 CEST 2009
Hello,
Was anyone aware we are doing the do_ram_command() wrong on the i8xx
nothbridges?
We are sending the ram commands to all memory and doing our dummy reads at
the end.
I just found an Intel doc that says we are supposed to do all the ram
commands to each row of memory.
Quoting from doc:
1. Steps for JEDEC initilization for SDRAM devices during boot up:
a. NOP command
b. Pre-charge all banks (at least 200 us after NOP)
c. 8 CBR refreshes (Auto Refresh)
d. MRS command
e. Set GMCH-M Mode Select bits back to NORMAL operation mode
f. Perform a dummy memory read cycle
2. Repeat this sequence for all memory rows for all SO-DIMMs
3. Test all memory rows after JEDEC initialization sequence is done on all
memory rows
I will work on a patch for the i830, we should probibly fix this on the
other Intle northbridges.
--
Thanks,
Joseph Smith
Set-Top-Linux
www.settoplinux.org
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