nb/intel/sandybridge: Clarify RAM overclock options
Rewrite them to more accurately describe what they are about.
Change-Id: Icb0ac1e592b662bbb81da431ff97af1a00f952c0
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47429
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin L Roth <gaumless@gmail.com>
diff --git a/src/northbridge/intel/sandybridge/Kconfig b/src/northbridge/intel/sandybridge/Kconfig
index 01aa11c..b7738a2 100644
--- a/src/northbridge/intel/sandybridge/Kconfig
+++ b/src/northbridge/intel/sandybridge/Kconfig
@@ -47,25 +47,32 @@
System Agent/MRC.bin. You should answer Y.
config NATIVE_RAMINIT_IGNORE_MAX_MEM_FUSES
- bool "Ignore vendor programmed fuses that limit max. DRAM frequency"
+ bool "[OVERCLOCK] Ignore CAPID fuses that limit max DRAM frequency"
default n
depends on USE_NATIVE_RAMINIT
help
- Ignore the mainboard's vendor programmed fuses that might limit the
- maximum DRAM frequency. By selecting this option the fuses will be
- ignored and the only limits on DRAM frequency are set by RAM's SPD and
- hard fuses in southbridge's clockgen.
- Disabled by default as it might causes system instability.
- Handle with care!
+ Ignore the CAPID fuses that might limit the maximum DRAM frequency
+ on overclocking-capable parts. By selecting this option, the fuse
+ values will be ignored and the only limits on DRAM frequency are
+ determined by SPD values, per-board devicetree settings and hard
+ limits in the northbridge's MPLL. Disabled by default as it can
+ cause instability.
+ Consider this to be an overclocking option. Handle with care!
config NATIVE_RAMINIT_IGNORE_XMP_MAX_DIMMS
- bool "Ignore XMP profile max DIMMs per channel"
+ bool "[OVERCLOCK] Ignore XMP max DIMMs per channel"
default n
depends on USE_NATIVE_RAMINIT
help
- Ignore the max DIMMs per channel restriciton defined in XMP profiles.
- Disabled by default as it might cause system instability.
- Handle with care!
+ The more DIMMs are in a channel, the more signal integrity worsens.
+ Because of this, some DIMMs only support running at XMP timings if
+ the number of DIMMs in the channel is below a limit. This limit is
+ usually 1, i.e. there must be no other DIMMs in the channel to use
+ XMP timings. Otherwise, non-XMP timings are used.
+ When this option is enabled, the max DIMMs per channel restriction
+ in XMP is ignored. Depending on available margins, this could work
+ but it can also result in system instability.
+ Consider this to be an overclocking option. Handle with care!
config NATIVE_RAMINIT_IGNORE_XMP_REQUESTED_VOLTAGE
bool "Ignore XMP profile requested voltage"