[coreboot] [PATCH] RS690 code booting RS740 with ECS A740GM-M

Wed Jan 19 22:23:49 CET 2011

Adds RS740 HT and internal graphics PCI ids. 
Adds support for RS740 in RS690 code (some of the fam10 code from RS780).
Adds support for ECS A740GM-M.

This definitely needs more patches and fine-tuning. 
Only tested on RS740.

Signed-off-by: Ivaylo Valkov <ivaylo at e-valkov.org>
---
Hello all,

And thank you for all the work you have done so far.

This is kind of long e-mail, so for the impatient - with these patches I
am able to initialize the RS740 chipset on the ECS A740GM-M motherboard and
boot GNU/Linux (with Xorg), but the code definitely needs more fine-tuning
and patching.

All my hardware died recently, so I bought two identical ECS A740GM-M
[1] replacement boards with AMD RS740/740G chipset as an opportunity to
help the coreboot project gather some information. The requested
information for flashrom and the RS740 chipset is attached. One thing
led to another and I've gone a lot further - the board seems usable.

Flashrom works on the board. The flash chip is recognised as MX25L8005,
but it is actually [2] MX25L8006. [3] In spite of that I was able to
flash it and boot the proprietary BIOS and coreboot. I've experienced
some CMOS checksum errors with the proprietary BIOS after flashing, but
everything worked fine after setting the date. This does not happen
always and I can't see a pattern when it does. Should I post the
flashrom related information on the flashrom mailing list?

With flashrom working and the information on this list (and few other
places) that the RS740 is RS690 with new graphics I decided to test the
RS690 code on the board. So, after nearly a month of cut-and-paste from
mahogany_fam10 and dmb690t, new code in RS690, borrowed from RS780, ACPI
from mahogany_fam10 for the board and some modifications I ended up
with something usable. The CPU is Sempron 140 (AM3/AM2+ socket).

I have some basic and blurry understanding of the boot process. I do not
know why exactly all that I've done worked. It is fair to say that I
have read almost zero documentation. All was achieved only by reading
the available code and observing the logic. Maybe it wasn't the smartest
and safest thing to do, but worth it.

So carefully review the code. Some of it is there so I could build. It
might be irrelevant. Patches are attached.

I used a cmos.layout from mahogany_fam10 to build, but images with
enabled CONFIG_USE_OPTION_TABLE (use CMOS/NVRAM values instead of hard
coded ones) in menuconfig do not boot at all - not even single serial
line of output. With recent changes and the move of CMOS to CBFS I can't
build with that option.

I am able to boot GNU/Linux. USB, network, sound, ATA and SATA are
working. PCI worked with external graphic and network card. PCIe is not
tested.

The master and stable releases of SeaBIOS hang when there is a USB mouse
connected after printing "USB mouse initialized". USB works fine under
GNU/Linux.

HT is initialized to 200MHz. The lspci output (also attached) after
coreboot loads, shows that 1.6GHz link frequency is possible. The
documented limit for RS690 is 1GHz. The RS780 code is implemented
differently, so it has k8 and fam10 support. Do you think it will be
possible to use something from RS780 code? I am not confident and
competent to make the changes myself, but I am willing to test patches
(any).

The lspci output for the board with coreboot running differs(in
places). I think it is ACPI and devicetree.cb related. Don't know how to
fix it right now.

After coreboot initializes the board, the CPU has two states - 1.9 GHz
and 2.7GHz. With proprietary BIOS the CPU can do two more - 1.5GHz and
800MHz.  That is ACPI issue, righ? Before adding ACPI the only possible
frequency was 2.7GHz.

The code that prints the CPU revision (in get_cpu_revision) is taken
from RS780. I think it prints (only that!) wrong revision - "K8_10"
instead of "Fam 10". It seems it should be "eax <= 0x100fff" instead of
"eax <= 0x100f00", but as I've said I didn't read enough documentation.

I've extracted a VGA BIOS image from the proprietary BIOS and the
internal graphics card worked. Both DVI and VGA connectors work. Xorg
loads, but if the resolution is higher than or equal to 1024x768 the
screen flickers and I see horizontal lines. [4] When the display is
refreshed (key press, mouse move, by programs) it is awful. [5] For
lower resolutions it is not noticeable or even missing. This is tested
on deblobed Linux-libre kernel only, and the drivers do not load the
binary-blob firmware for 3D acceleration.

Is it possible to initialize the internal graphics on RS690/RS740 from
coreboot code and use VGA BIOS image from SeaBIOS? Like it is done for
the M2V-MX SE board? Yes I know it uses VIA chipset and it has
documentation. I guess what I am asking is, is it there enough
documentation released by AMD to make it work. I've hacked a PCI header
for the VGA BIOS image from SeaBIOS, so it can be loaded by coreboot
(vendor/device ID complains). The ROM is loaded, but SeaBIOS hangs. Not
that I was expecting to just work.

There are microcode patches for some CPUs that are non-free binary-blobs
(examine their license headers). Is it possible to make loading such
microcode configurable? I am unable to build the fam10 code without a
microcode filename. I understand that AMD (and other companies) might
not want to release such information for various reasons, but I prefer
to use "crippled" CPU instead of non-free microcode, when I am running
free software BIOS. Do I really need them for Sempron anyway? It works
without them. Didn't notice any difference in performance with them. Not
that the current state of the board can be used for measuring
performance. The work-around I am using right now is zero-filled
microcode patch file in the board directory, that does nothing.

Images of the board and the chips can be found on my "web site" [6].

I've copied the copyright notices from files that had such and I've used
code from. For the rest I've put a comment pointing to the file I've
borrowed from. Hope that is the right way to do it. Unfortunately the
code I used restricts me to GPLv2 only, I prefer GPLv2(or later).  What
is the policy on GPLv3 (or later) code for that matter? Just thinking
for possible future contributions.

P.S. This is a lot of information (and issues). If anything has to go in
the issue tracker I will do it.

[1] http://www.ecs.com.tw/ECSWebSite/Product/Product_Detail.aspx?CategoryID=1&DetailID=1083&DetailName=Feature&MenuID=1&LanID=0
[2] http://e-valkov.org/coreboot/ecs-a740gm-m-bios-chip.jpg
[3] http://www.mxic.com.tw/QuickPlace/hq/PageLibrary4825740B00298A3B.nsf/h_Index/6F878CF760C559BD482576E00022E6CC/?OpenDocument&EPN=MX25L8006E
[4] http://e-valkov.org/coreboot/video-card-1.ogv
[5] http://e-valkov.org/coreboot/video-card-2.ogv
[6] http://e-valkov.org/coreboot/

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