XO1.5 WLAN power ECO

Scope

This describes a change to early prototypes of the XO-1.5 motherboard. It fixes a problem with the VX855 chip maintaining power on one of it's SDIO ports when the system enters suspend. Boards without this ECO will loose their wireless network interface after being suspended.

This only applies to XO-1.5 B2 phase motherboards.

There was a different solution used during testing, which powers the WLAN whenever the laptop is either suspended or running. This solution is marginal, and deprecated.

Problem Description

The third SDIO port on the VX855 can't maintain power through a suspend. This ECO moves the control pin to an embedded controller GPIO10 at U28.37.

Procedure

1. Cut the trace between the via and Q38, pin 2.
2. Remove R398 (located on the "top" side of the motherboard, underneath the EC.)
3. Wire Q38, pin 2 to the side of R398 that is not connected to R401.

B3 Test Procedure

In order to test firmware for the B3 build, the following hybrid ECO is performed. Do not do this unless you are testing B3 firmware on a B2!

In this ECO, the EC is placed in control of the power to the internal SD slot, not WLAN.

1. Cut the trace between the via and Q28, pin 2 (not the trace from Q28.2 to R268).
2. Remove R398 (located on the "top" side of the motherboard, underneath the EC.)
3. Wire Q28, pin 2 to the side of R398 that is not connected to R401.