Exynos5420: ddr3: fine tuning the DDR3 timing values

Fine tuning DDR timings value for better stability

* Changed Data Driver Strength from 34 ohms to 30 ohms, expected to
  enhance signal integrity.
* Changed DQ signal from 0xf to 0x1f000f, to keep default value safe.
* Changed mrs[2] and added new mrs direct command for setting WL/RL
  without resetting DLL.
* Added explicit reset value write in phy_con0 instead of just setting
  a bit, to ensure that reset happens.
* Added DREX automatic control for ctrl_pd in none read memory state.

This is ported from: https://gerrit.chromium.org/gerrit/61405
Signed-off-by: David Hendricks <dhendrix@chromium.org>

Change-Id: I59e96e6dede7b49c6572548aca664d82ad110bb1
Reviewed-on: https://chromium-review.googlesource.com/66995
Reviewed-by: ron minnich <rminnich@chromium.org>
Commit-Queue: David Hendricks <dhendrix@chromium.org>
Tested-by: David Hendricks <dhendrix@chromium.org>
(cherry picked from commit ec34b711c6d270672c56d45c370ca14c0aa27ca3)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6611
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
4 files changed