gsctool -a -o error / CCD cable issues on Jubilant board.

[MD7070B]

I have a Jubilant-based Acer CB which I am trying to flash with the UEFI_Full firmware, in order to run Linux.

I understand this model requires a CCD cable to unlock and flash the UEFI firmware, so I have built one. Based on this source, a 56k resistance between CC2 and VBUS can be used, which is what I have done. I did notice however that this source says a 45.3k resistance is more suitable, so I am not 100% sure which is best.

Anyhow, I am trying to follow the instructions here: https://docs.mrchromebox.tech/docs/firmware/wp/disabling.html, but having limited success. The Chromebook is now showing up as a serial device on my other device when the two are connected via CCD cable. I have tried different ports and orientations.

This morning, trying the instructions again from the top down, I noticed that after running gsctool -a -o to enable CCD, and pressing the PP button as requested, after a few cycles of pressing the button and waiting, I get an error message and then the CB reboots. The biggest problem is this happens very quickly, to the point that I cannot read the full error message - I'm pretty sure I saw "error" in the terminal output though...

I would appreciate any advice to get around this, as this is a bit of an urgent project.

[MD7070B]

I will add that after the error message is displayed and the CB reboots, it gives a Black & White text message "Your device is finishing an update. This may take 1-2 minutes. Please do not turn off your device".

It has done this multiple times to I assume it is not "finishing the update". Don't know if that's making any difference...

To give a bit more information, back in VT2 logged in as root, running gsctool -a -o again does nothing. No prompts for PP button this time. gsctool -a -I returns the following:

State: Opened
Password: None
Flags: 000000
Capabilities, current and default:

  Capability               Current   Default
  ───────────────────────────────────────────
  UartGscRxAPTx            Y         Always
  UartGscTxAPRx            Y         Always
  UartGscRxECTx            Y         Always
  UartGscTxECRx            Y         IfOpened
  UartGscRxFpmcuTx         Y         Always
  UartGscTxFpmcuRx         Y         IfOpened
  FlashAP                  Y         IfOpened
  FlashEC                  Y         IfOpened
  OverrideWP               Y         IfOpened
  Reboot ECAP              Y         IfOpened
  GscFullConsole           Y         IfOpened
  UnlockNoReboot           Y         Always
  UnlockNoShortPP          Y         Always
  OpenNoTPMWipe            Y         IfOpened
  OpenNoLongPP             Y         IfOpened
  RemoveBatteryBypassPP    Y         Always
  I2C                      Y         IfOpened
  FlashRead                Y         Always
  OpenNoDevMode            Y         IfOpened
  OpenFromUSB              Y         IfOpened
  OverrideBatt             Y         IfOpened
  AllowUnverifiedRo        Y         Always    (Never)

CCD caps bitmap: 0x3fffff
Capabilities are modified.

[MD7070B]

I'm starting to suspect my CCD cable. I used a 56k resistor between CC2 and VBUS, as mentioned.

Could it be that the slight deviation in resistor value is the cause of the issue here?

[MrChromebox]

unfortuantely I've never build a CCD cable myself nor used a Brox-based device like Jublilant. That said, the process to open the CCD does not require a cable to be connected, so the error is unlikely related to the cable

[MD7070B]

I started to suspect my CCD cable of being the problem, so I changed the resistors to create a resistance of very close to 45.3k ohms between CC2 and VBUS, as recommended.

Still not having any luck, so far. I ran dmesg -w on the Chromebook I am trying to flash, and when plugging the CCD cable in (to the USB C port, the other end is plugged into another Linux computer), I notice a couple of messages appear:

cros_ec_ucsi cros_ec_ucsi.3.auto UCSI_GET_PD_MESSAGE failed (-5)

Not sure what this means of if relevant at all.

[MrChromebox]

again, gsctool -a -O has no requirement that a CCD cable be connected. Any failure there is completely separate and unrelated to any issues with the cable

[MD7070B]

gsctool -a -o seems to have succeeded now. No idea what was causing the error before. When I went to investigate the error message flashing up with a slow-mo camera, it had disappeared - was working fine.

Still having issued with CCD though. I think I may have found the issue in my CCD adapter - or connection method more accurately - using a female USB-C breakout (fine, in itself), but I think the USB C cable may not be passing through the required lines to the male end plugged into the Jubilant.

I'm going to try a female [edit, male] USB-C breakout next.

[MD7070B]

Tried a male USB-C breakout. Eventually managed to get the host to at least recognise there was something connected - my recognise I mean spit out a load of enumeration errors. But despite considerable effort I have failed to get the host to recognise the Jubilant as a serial device.

Interestingly:

• I added a small THT Red LED (plus current limiting resistor) on my adaptor board between VCC and GND, to give a visual on the status of power at least. (Edit to clarify, this has been there since the start).
• Obviously this lights when the USB-A end is connected to a host.
• With the (non-functional) female USB-C breakout, and Male to Male USB-C cable, the LED also lit when the USB-C end was connected to the Jubilant, and the host end not plugged in (E.G receiving power from the Jubilant).
• With the new male USB-C breakout, the LED only lights when the host end (USB-A) is connected to something. Not sure if this may be significant.

Odd thing is I have done quite a bit of testing with a meter on my adapter, and there seems to be continuity where there should be, and the resistances on CC1 and CC2 are very close to what they are supposed to be. But it just won't work or give consistent results!

[MD7070B]

I have tried another pinout on my USB-C CCD adapter, and this, finally, worked! I was able to get a serial connection to the CB, and ran the CCD commands:

echo "wp false" > /dev/ttyUSB0
echo "wp false atboot" > /dev/ttyUSB0
echo "ccd reset factory" > /dev/ttyUSB0

Running crossystem wpsw_cur returns 0. Brilliant.

However, when launching the firmware utility script, the UEFI Firmware option is greyed out:

(Sorry about the poor image!)

That was run as chronos user. I tried using option 5 to backup the current firmware to a USB disk first, which succeeded, but made no difference to the UEFI availability.

I did notice that gsctool -a -I reports:

State: Opened
**Most parameters are Y Always or Y Always (IfOpened)**
AllowUnverifiedRo: Y Always (Never)

That last line looks a bit odd to me. I thought the CCD process should have set this to always as per the docs:

If you disabled firmware WP via CCD and reset your CCD flags with ccd reset factory (as per the instructions above), you can skip this step, as ccd reset factory will set AllowUnverifiedRo to always.

How can I access the UEFI option?

[MrChromebox]

How can I access the UEFI option?

I've enabled it in the script now, just be aware it's untested, and if it doesn't boot, I'll need to give you a debug-enabled version to troubleshoot it

[MD7070B]

Thank you. I assume you mean it hasn't been specifically tested on Jubilant boards?

I ran it anyway. I did get a message about ensuring that I had set the FlashAP Always flag using my CCD cable, to aid the recovery process in case anything went wrong - I was not sure what to do here, I have not read anything on your site regarding a FlashAP Always flag - maybe I missed it?

I decided to proceed anyway. The UEFI install seemed successful. I have now been testing a few ways of installing Ubuntu desktop - the has presented a couple of challenges (such as a bug in the Ubuntu installer when handling the partitions left on the disk from ChromeOS), but nothing that seems to be linked to the UEFI / firmware.

Thanks for your support.

[MrChromebox]

glad to hear it's working well!

ccd reset factory will set all flags to Y - the message is just telling you that unbricking is harder without that flag set.

[MD7070B]

Thanks for your help!

Latest issue though is getting my trackpad to work in Ubuntu! I remember having this issue on my older Chromebook when I trialled this, and I am sure there was some fairly trivial fix. But, here I am struggling with it again!

[MD7070B]

Thanks for your help!

Latest issue though is getting my trackpad to work in Ubuntu! I remember having this issue on my older Chromebook when I trialled this, and I am sure there was some fairly trivial fix. But, here I am struggling with it again!

Fixed that one, the latest challenge is that Ubuntu prompted to reboot to finish installing updates. I selected Reboot now. After doing so, the laptop only powered on to a black screen, with keyboard backlight illuminated, and fans running. Nothing else. Tried a hard power-off and start again, same result.

I'm not even seeing the firmware splash screen at this point!