[coreboot] Intel 8xx northbridge ram init is wrong

Joseph Smith joe at settoplinux.org
Sun Jun 7 08:37:13 CEST 2009

On Tue, 02 Jun 2009 11:13:30 -0400, Joseph Smith <joe at settoplinux.org>
> 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
> 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
> memory rows
> I will work on a patch for the i830, we should probibly fix this on the
> other Intle northbridges.
Good news :-)
I have the above method working on the i830. 
I just want to do a little more testing before I submit a patch.
Joseph Smith

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