[coreboot] v2[PATCH]RCA RM4100 i82830 support

[joe at smittys.pointclark.net]

Quoting Corey Osgood <corey.osgood at gmail.com>:

> On Tue, 2008-02-26 at 21:33 -0500, joe at smittys.pointclark.net wrote:
>> Quoting joe at smittys.pointclark.net:
>>
>> > Quoting Corey Osgood <corey.osgood at gmail.com>:
>> >
>> >>
>> >> On Tue, 2008-02-26 at 16:19 -0500, joe at smittys.pointclark.net wrote:
>> >>> >> +static void do_ram_command(const struct mem_controller *ctrl,
>> >>> >> uint32_t command, uint32_t addr_offset)
>> >>> >> +{
>> >>> >> <snip>
>> >>> >> +
>> >>> >> +	/* Read from (DIMM start address + addr_offset). */
>> >>> >> +	read32(0 + addr_offset);	//first offset is always 0
>> >>> >> +}
>> >>> >
>> >>> > This isn't ready for multiple dimms yet. See the cn700 patch I
>> >>> > recently sent (but haven't committed yet, I think it was acked).
>> >>> >
>> >>> Oh you mean this? What do I need to do to adapt it for the i82830?
>> >>>
>> >>> +	/* NOTE: Dual-sided ready */
>> >>>   	read32(0 + addr_offset);
>> >>> +	for(i = 0; i < (ARRAY_SIZE(ctrl->channel0) * 2); i++) {
>> >>> +		reg8 = pci_read_config8(ctrl->d0f3, 0x40 + i);
>> >>> + 	if(reg8) read32((reg8 << 26) + addr_offset);
>> >>> + }
>> >>
>> >> This reads from register 0x40 + i, where 0x40 is the top of the first
>> >> dimm, and i counts to the max number of dimms.
>> >
>> > Why read this from a register?? Why not just use (i = 0; i <
>> > DIMM_SOCKETS; i++)
>
> ARRAY_SIZE(ctrl->channel0) is the number of spd addresses, which can be
> less than the max number of dimms.
>
>> >
>> >> Reg 0x40 contains bits
>> >> 33:26 of the top address, hence the << 26. So you'd need to adjust both
>> >> of these to fit the i830's DRB mechanism. If the i830 uses an ugly
>> >> format like the i810 does, then it may be easier to store the size in
>> >> scratch registers somewhere after it's calculated, and then use those
>> >> values instead. Sorry I can't get more specific, I've got to head out to
>> >> my next service call.
>> >>
>> > The DRB i830 is not ugly it is very simple, simple, simple. So simple
>> > that it just calculates the memory size in ticks of 32 per side
>> (Sorry typo I meant) +
>> > the next side up to 4 sides. Like this:
>> >
>> > Example: 128MB SINGLE sided so-dimm in slot 1
>> >           128MB DOUBLE sided so-dimm in slot 2
>> >
>> > There are 4 DRB registers(actually 6 but but only 4 that are usable -
>> > Intel design glitch), 1 for each side. So in this example they would
>> > look like this:
>> >
>> > DRB1 = 0x04
>> > DRB2 = 0x04
>> > DRB3 = 0x06
>> > DRB4 = 0x08
>> >
>> > So if we needed to convert this we would do something like this (DRB *
>> > 32) * 1024 correct? But if we just need to calculate the end of
>> > so-dimm #1 and the start of so-dimm #2 the only important register
>> > would be DRB2 (side 2 of so-dimm #1) and DRB3(side 1 of so-dimm #2),
>> > correct?
>
> The modified version would be something like
> read32(0 + addr_offset);
> for(i = 0; i < ARRAY_SIZE(ctrl->channel0); i++) {
> 	reg8 = pci_read_config8(ctrl->d0/*?*/, DRB1 + i);
> 	read32(reg8 * 32);
> }
>
Ok starting to make sense but what is all this about? /*?*/ wouldn't  
it just be reg8 = pci_read_config8(ctrl->d0, DRB1 = i);
This is going to show our results in MB, is that what we want? For  
accuracy shouldn't it be in bytes? Sorry for so many questions, I just  
want to get this right.


Thanks - Joe