Ticket #9377 (closed specification: fixed)

Opened 5 years ago

Last modified 5 years ago

OFW needs to not enable serial port when "serial enable" jumper is missing

Reported by: wad Owned by: wmb@…
Priority: normal Milestone: Not Triaged
Component: ofw - open firmware Version: Development firmware
Keywords: Cc:
Action Needed: never set Verified: no
Deployments affected: Blocked By:


Now that keyboard and DCON are working on XO-1.5, we need to test the camera. This requires that OFW not enable the serial port on startup, when the "Serial Enable" jumper is missing, and continue to work as it does currently (q3e03) when the jumper is present.

The Serial Enable jumper is connected to VGPIO1 on the VX855, and will be pulled low when a jumper is present.

Change History

Changed 5 years ago by wmb@…

Sadly, the string "VGPIO1" does not appear in either the VX855 Chrome9 Programming Manual or the VX855 System Programming Manual. Correlating nomenclature between the different VIA documents has proven to quite a time sink...

Changed 5 years ago by wmb@…

  • owner changed from wmb@… to wad
  • component changed from ofw - open firmware to hardware

According to Patrick Chen of Via:

As your found, the GPM only describes VGPIO 2/3/4. I double check logic designer directly and the answer is VGPIO1 is useless but it is not removed from ball out map to be NC. Please apply VGPIO 2/3/4.

I'm reassigning to hardware so the pin can be moved.

Changed 5 years ago by wad

  • owner changed from wad to wmb@…
  • component changed from hardware to ofw - open firmware

I apologize for that slight problem.

We will instead connect the SERIAL_EN signal to the VX855 BATLOW# input, U19, ball AJ21 (page 15). There is an internal 8K resistor on this input.

There is an unpopulated pull-up resistor (R126) which can be used for testing on A1/A2, and this will be fixed in B1 hardware. R126 can be found on the top side of the motherboard (nearest the LCD), between the area below the VX855 and the LCD connector.

Reassigning to OFW, with a low priority...

Changed 5 years ago by wmb@…

  • status changed from new to closed
  • resolution set to fixed

Fixed by svn 1311, Q3A09.

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