nb/intel/sandybridge: Refine power-down mode logic

When memory is running at fast frequencies, power-down modes can lessen
system stability. Check tXP and tXPDLL values and use safer power down
modes if their values are high. Do not use APD with DLL-off on mobile:
vendor firmware does not use it, and it can influence system stability.

Change-Id: Ic8e98162ca86ae454a8c951be163d58960940e0e
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47746
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

0 files changed, 0 insertions, 0 deletions