[coreboot] [patch] i82810 WIP for fixing VGA and 512MB
Elia Yehuda
z4ziggy at gmail.com
Mon Nov 17 15:49:03 CET 2008
On Mon, Nov 17, 2008 at 3:58 PM, Stefan Reinauer <stepan at coresystems.de>wrote:
> Elia Yehuda wrote:
> > Those 2 patches are one step towards having a working Onboard-VGA
> > and 512MB (the max for i810). The raminit.c patch fixes some
> > misconfigurations and probes the DIMMs correctly (all dual-sided are
> > now recognized properly), and also set buffer_strength to handle 2
> > DIMMs although atm this doesn't work. The i82810/northbridge.c patch
> > takes care of allocating Onboard-VGA memory.
> >
> > Signed-off-by: Elia Yehuda <z4ziggy at gmail.com <mailto:z4ziggy at gmail.com
> >>
>
> Good work!
thanks :)
>
>
> But no ack yet, because it's ongoing work that also breaks some
> (potentially) working cases. I have a couple of comments though
>
> > + for (i = 0; i < DIMM_SOCKETS ; i++) {
> > + dimm_size = smbus_read_byte(ctrl->channel0[i], 31);
> > + dimm_banks = smbus_read_byte(ctrl->channel0[i], 5);
> > + if (dimm_size) {
> Can this be changed to read the size and banks values from the PCI
> registers or variables instead of from the smbus?
> It's a lot of slow, unneeded bus traffic for every ram read. I don't
> know about the 810, but other Intel chipsets would get confused by that
> kind of bus traffic and delays at that point.
>
i had no idea using the smbus is slower.
actually my initial hacking was using the PCI but it was a bit more
complexed
since i had to convert from intel's codes to MBs, and i had a bit of a
problem
detecting the dimm_bank properly - i will look into that again when i'll
wake up...
>
> > + * Rows of Slot 1 are numbed 2 through 3. The
> > + * DIMM’s SPD Byte 5 describes the number of
> sides in a
> > + * DIMM; SPD Byte 13 provides information on
> Some weird character sneaked into that comment.
the evil char is now gone...
>
>
> > );
> > + uint8_t val;
> > + val = pci_read_config8(ctrl->d0, DRAMT);
> I suggest using PCI_DEV(0,0,0) instead of the indirection ctrl->d0 all
> over raminit.c.
>
> That indirection was invented for AMD K8 where in an SMP environment
> there are several memory controllers with several DIMMs attached to
> each. But the i810 definitely only supports a single memory controller,
> and the code can be kept a lot simpler.
actually using ctrl->d0 looks cleaner in the code (rather than using
PCI_DEV(0,0,0))
but sure, i'll change it...
>
>
> > + if ((smbus_read_byte(ctrl->channel0[i], 127) | 0xf)
> == 0xff) {
> Same here: Intel boards expect the SPD ROMs at fixed places, unlike the
> common case on Opteron boards.
will look into that.
>
>
> Also, your code only treats single channel configurations. Is the i810
> capable of dual channel operation?
the i810 supports 2 SDRAM DIMM slots, single and dual sided, up to 512MB
total.
i have no idea how to treat the 2nd slot, although ive read the datasheet
top-to-bottom.
any clues would be greatly appreciated...
>
>
> > - /* TODO: This needs to be set according to the DRAM tech
> > + /* TODO: This needs to be calculated according to the DRAM tech
> >
> Don't think this can really be calculated. Looking at your findings
> below, you should probably use a table for this and look up the correct
> values from the table.
> > * (x8, x16, or x32). Argh, Intel provides no docs on this!
> > * Currently, it needs to be pulled from the output of
> > * lspci -xxx Rx92
> > + * here are some common results:
> > + * value: tom: config:
> > + * 0x3356 256MB 1 x 256MB DIMM(s), dual sided
> > + * 0x0001 512MB 2 x 256MB DIMM(s), dual sided
> > + * 0x77da 128MB 1 x 128MB DIMM(s), single sided
> > + * 0x55c6 128MB 2 x 128MB DIMM(s), single sided
> > + * 0x3356 128MB 1 x 128MB DIMM(s), dual sided
> > + * 0x0001 256MB 2 x 128MB DIMM(s), dual sided
> > */
> Because:
> > - pci_write_config16(ctrl->d0, BUFF_SC, 0x77da);
> > + /* use 2 dual sided DIMMs - this also works with only 1 DIMM */
> > + pci_write_config16(ctrl->d0, BUFF_SC, 0x0001);
> > +
> This fixes one case and breaks another one. Not really an improvement.
not really. using 0x0001 works fine for both 1 DIMM and for 2 DIMMs
(currently
my i810 is active, using 1 256MB DIMM, with 0x0001 setting). using the
0x77da
is worse since it only works with 1 single-sided DIMM. after I'll fix the
2nd DIMM
issue (ie, make it work!!) i'll deal with those small issues.
>
>
> > + /* set the GMCH to prechange all during the service of a page miss
> */
> >
> precha_r_ge?
yep. prechange. looks weird? talk to the intel ppl - i copied this line from
the datasheet...
>
>
> > + /* or we can use sane defaults, but VGA won't work for unknown
> reason */
> > + //pci_write_config8(ctrl->d0, PAM, 0x41);
> This will prevent writes to the CSEG, will it? (Didn't check)
yep, from CSEG and FSEG. i tried putting this at the end of sdram_enable()
but
it always causes the VGA not to work, so i left it for now with the "insane"
range
for r/w.
the original BIOS shows 0x41 at this offset, but i have no idea after which
step
does it set it to make the VGA still work. maybe im missing someting else?
>
>
> > + /* setting Vendor/Device ids - there must be a better way of doing
> > + * this...
> > + */
> > + /* set vendor id */
> > + val = pci_read_config16(ctrl->d0, 0);
> > + pci_write_config16(ctrl->d0, 0x2c, val);
> > + /* set device id */
> > + val = pci_read_config16(ctrl->d0, 2);
> > + pci_write_config16(ctrl->d0, 0x2e, val);
> Yes, during pci_set_subsystem_ids in northbridge.c:
>
> static void intel_set_subsystem(device_t dev, unsigned vendor, unsigned
> device)
> {
> u32 pci_id;
>
> printk_debug("Setting PCI bridge subsystem ID\n");
> pci_id = pci_read_config32(dev, 0);
> pci_write_config32(dev, PCI_SUBSYSTEM_VENDOR_ID, pci_id );
> }
>
> static struct pci_operations intel_pci_ops = {
> .set_subsystem = intel_set_subsystem,
> };
>
> static struct device_operations mc_ops = {
> [..]
> .ops_pci = &intel_pci_ops,
> };
many, many thanks :) i'm still learning the coreboot code (im just hacking
around for
about 2 weeks) and i figured there must be a better way of doing this, just
couldnt
figure out how...
>
>
> > /* 3. Perform 8 refresh cycles. Wait tRC each time. */
> > PRINT_DEBUG("RAM Enable 3: CBR\r\n");
> > - do_ram_command(ctrl, RAM_COMMAND_CBR, 0, row_offset);
> > for (i = 0; i < 8; i++) {
> > + do_ram_command(ctrl, RAM_COMMAND_CBR, 0, row_offset);
> > + /* FIXME: are those read32() needed? */
> > read32(0);
> > read32(row_offset);
> > udelay(1);
> Probably not needed the way you're doing it now. The reads cause a
> refresh cycle on a given dram rank. do_ram_command does one such read.
> Since several are needed they were done in a loop.
thank for clearing this out. just a remark - do_ram_command already did
read32()
commands before my patches, it simply didn't do it on all slots/banks.
>
>
> Since do_ram_command does more stuff than just those reads, you might
> cause the controllers state machine to choke.
>
> Basically, doing any reads in do_ram_command() is a bad idea. They
> should instead be done when/where they need to happen. I suggest looking
> at the i945 code for an example.
i don't know any other way of doing the do_ram_command() properly. i've used
mainly
the i830 code as a reference - i can't seems to find any i945 code.
>
>
>
>
> Stefan
again, many thanks for your insights and corrections. and since we're on the
subject -
can we remove the redundant row_offset which is not used anywhere in the
code?
Elia.
>
>
>
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