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mb/google/fizz: Skip FSP init for UART 0 

The GPIO pins for UART 0 on Fizz are routed to the add-in card slot
and should not be used as a UART device.  coreboot is setting the
pins to GPIO Mode but FSP is re-configuring them for Native Mode
and the behavior is unexpected when the kernel tries to initialize
the UART device.

The UART 0 device is PCI function 0 so it needs to be enabled for
other functions to be visible to the OS so it can't just be disabled.
Instead, set the device to PchSerialIoSkipInit so that FSP will not
change the pin state.

BUG=b:73006317

TEST=Tested with add-in card on fizz hardware to ensure the pin state
does not change when FSP runs or the kernel boots.

Change-Id: Id97c1e482ef0d5642fcf9018d802e1d0e073263d
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/24973
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
This commit is contained in:
Duncan Laurie 2018-03-02 14:39:47 -08:00 committed by Patrick Georgi
parent 069ca66ea4
commit 3879ef49ea
1 changed files with 1 additions and 1 deletions
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2
src/mainboard/google/fizz/devicetree.cb
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@ -304,7 +304,7 @@ chip soc/intel/skylake
[PchSerialIoIndexI2C5] = PchSerialIoPci,
[PchSerialIoIndexSpi0] = PchSerialIoPci,
[PchSerialIoIndexSpi1] = PchSerialIoDisabled,
[PchSerialIoIndexUart0] = PchSerialIoPci,
[PchSerialIoIndexUart0] = PchSerialIoSkipInit,
[PchSerialIoIndexUart1] = PchSerialIoDisabled,
[PchSerialIoIndexUart2] = PchSerialIoSkipInit,
}"