New subject: [PATCH] ASUS P2B-LS support, RAM detection for 440BX, add Slot 1 CPU, Microcode for Intel Tualatin CPUs

5 Mar 2010


      On Fri, 05 Mar 2010 15:24:25 +0100, Stefan Reinauer stepan@coresystems.de
wrote:
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On 3/5/10 3:15 PM, Joseph Smith wrote:
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On Fri, 05 Mar 2010 13:04:27 +0000, Mark Marshall
mark.marshall@csr.com
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wrote:
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Joseph Smith wrote:
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On 03/05/2010 03:03 AM, Mark Marshall wrote:
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On 04/03/10 13:10, Joseph Smith wrote:
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On 03/04/2010 07:38 AM, Joseph Smith wrote:
> On 03/04/2010 07:30 AM, Uwe Hermann wrote:
>
>> On Thu, Mar 04, 2010 at 10:05:57AM +0000, Mark Marshall wrote:
>>
>>> On 03/03/10 04:19, Keith Hui wrote:
>>> The first problem is that this motherboard only has three DIMM
>>> slots. This means you have to set SDRAMC to something different;
>>> 0x0103 works for me.
>>>
>>>
>> Hm, seems to be determined by SDRAMPWR + MMCONFIG, and MMCONFIG
>> seems to
>> be a hardware-strap (so we can check it), but not sure about
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SDRAMPWR.
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>>>
I think a simple SPD probe would work, if the correct value is
returned
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you know you have memory in that slot, otherwise if 0xff is returned
then no memory is present. Do this probe for as many slots as the
440
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supports. Then set your registers based on that.
The issue here is the number of DIMM slots on the motherboard, not
the
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number of sticks in the slots. Some 440BX boards have four slots,
while
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others only have three.
MM
That is fine. Then if 440bx datasheet says it supports 4 slots, then
that should be the standard.
Please check this section of the 440BX data sheet.
3.3.24 SDRAMC—SDRAM Control Register (Device 0)
We are interested in bit 4.
SDRAMPWR. The SDRAMPWR bit controls how the CKE signals are driven
  for different DRAM configurations. For a 3 DIMM configuration,
  SDRAMPWR should be set to ‘0’. For a 4 DIMM configuration,
  SDRAMPWR should be set to ‘1’. In this case the 82443BX drives a
  single CKE signal (GCKE). The combination of SDRAMPWR and MMCONFIG
  (DRAMC register) determine the functioning of the CKE signals.
  Refer to the DRAMC register (Section 3.3.15, “DRAMC—DRAM
  Control Register (Device 0)” on page 3-19) for more details.
Note: When PCIRST# assertion occurs during POS/STR, these bits
  are not reset to 0.
As far as I can tell we cannot auto-detect this.  Some (many)
440BX boards only have three DIMM slots, and in these cases the
clocks are routed differently to the boards with four DIMM slots.
That's easy... so you do something like this:
slot4_detect = (spd_read_byte((DIMM_SPD_BASE + 3), SPD_MEMORY_TYPE);
if (slot4_detect != 0xff) {
 /* We have 4 slots */
 ----Set bit 4 in SDRAMPWR----
 #define DIMM_SOCKETS 4

} else {
 /* We have 3 slots */
 ----Set bit 4 in SDRAMPWR----
 #define DIMM_SOCKETS 3

}
Hope that helps.
Will a mainboard with three modules but 4 slots work like this? Can
someone try? If we can autodetect it, we should. If we can't I think
encoding the number of slots in Kconfig is fine.
I think so, from what I understand the clocks are routed in a daisy chain
so to speak. So if there is 4 physical slots and the system is only
configured for three it should work ok. Also this routine will be
determined at every start up so if you put a sdram module in the fourth
slot it will be re-configured for 4 slots.
Anyways the only way to know if this will work is to test it so can someone
please test?
Also, one could always use serialice on a 4 slot system with factory bios
to see how they deterime it....
One could try a dump with three DIMMS and then a dump with four DIMMS and
compare the results.
-- 
Thanks,
Joseph Smith
Set-Top-Linux
www.settoplinux.org

Re: [coreboot] [PATCH] ASUS P2B-LS support, RAM detection for 440BX, add Slot 1 CPU, Microcode for Intel Tualatin CPUs