Unable to get S3 resume to work on new port

[Kevin Keijzer]

Hello,

I'm working on a port for a new board; the ASRock B75M-ITX.

A friend of mine did the initial porting [1] based on the existing B75 
Pro3-M and autoport. I then took over the board as I intend to build an 
HTPC around it.

Everything works fine, with the exception of resuming from S3. The board 
goes to sleep fine, but when I resume it, I'm greeted with the payload. 
(As this board does not have a serial port, I don't have an easy way to 
get logs, but everything looks like it just does a cold boot because 
DRAM is reset.)

Then I found out that on the ASRock B75 Pro3-M port, which has been in 
coreboot since 2017, S3 resume also does not work [2]. It is suggested 
there to find the proper DRAM_RESET_GATE_GPIO, so I tried that.

I've compiled and flashed roms with DRAM_RESET_GATE_GPIO set in Kconfig 
from 0 to 75, but in all cases the board just reboots instead of resumes.

So I'm not too sure what to try next. Does anyone have any suggestions?

[1] https://review.coreboot.org/c/coreboot/+/73097
[2] https://review.coreboot.org/c/coreboot/+/20227

[Kevin Keijzer]

Ok, so I just found out that for the H77 Pro4-M port [1], S3 resume is 
listed as working.

I built a ROM for that target and flashed it to my B75M-ITX, and now 
resume from S3 just works. (Other things are broken though, like ethernet.)

So I guess I have to compare these two targets now and find out what 
would be the fix?

[1] https://review.coreboot.org/c/coreboot/+/45317

[Kevin Keijzer]

I found the issue. 3VSBSW# had to be enabled for S3 resume to work.

It ended up being a oneliner fix in devicetree.cb:

device pnp 2e.a on
+	irq 0xe4 = 0x10		# + enable 3VSBSW#

[Peter Stuge]

Kevin Keijzer via coreboot wrote:
> I found the issue. 3VSBSW# had to be enabled for S3 resume to work.
>
> It ended up being a oneliner fix in devicetree.cb:
>
> device pnp 2e.a on
> irq 0xe4 = 0x10		# + enable 3VSBSW#

Good find!

Can you please push a commit with the fix to gerrit?

Thanks

//Peter