Persimmon: drop useless DDR3 voltage code copied from Inagua

Inagua can use GPIOs 178,179 to switch VMEM to 1.5, 1.35 or 1.25 V,
which it does according to data read from the SO-DIMM's SPD EEPROM.

On Persimmon (according to DB-FT1 rev. D schematics) both GPIOs are
unconnected, there is no way to change the 1.5 V DDR3 voltage (save
unsoldering a resistor). The whole code copied over from Inagua is
useless.

Removed the code, instead a comment hints at Inagua, for people who do designs
based on Persimmon but do have a way to change VMEM.

The line ...->DDR3Voltage = VOLT1_5; is supposed to make the AGESA DDR3 code
select the RAM timings for the actually supplied voltage instead of the
hoped-for but unavailable lower voltage. I have no idea how to test this, but
in any case it can't hurt.

Change-Id: Id098e09418b665645814a6ee2d41a3bff72238ba
Signed-off-by: Jens Rottmann <JRottmann@LiPPERTembedded.de>
Reviewed-on: http://review.coreboot.org/2448
Tested-by: build bot (Jenkins)
Reviewed-by: Peter Stuge <peter@stuge.se>

0 files changed, 0 insertions, 0 deletions