[coreboot] Intel 8xx northbridge ram init is wrong

Joseph Smith joe at settoplinux.org
Tue Jun 2 17:13:30 CEST 2009

Was anyone aware we are doing the do_ram_command() wrong on the i8xx
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.

Joseph Smith

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