Angel Pons has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/57261 )
Change subject: skylake: Default to `BOARD_TYPE_DESKTOP` for PCH-H ......................................................................
Patch Set 3:
(1 comment)
Patchset:
PS3:
This also changed the type for mobile boards. I have to admit […]
Oh, I completely forgot about Halo. Looks like the only board where this change would have a meaningful impact is kontron/bsl6.
Looking at the code, this setting only affects the initial DIMM ODT settings that MRC uses:
``` +----------------+--------------------------+--------------------------+ | Platform type | Mobile and ULT | Desktop and Halo | +------+---------+-------+--------+---------+-------+--------+---------+ | MemR | RttType | RttWr | RttNom | RttPark | RttWr | RttNom | RttPark | +------+---------+-------+--------+---------+-------+--------+---------+ | DDR3 | 1DPC 1R | 120 Ω | Off | N/A | 60 Ω | Off | N/A | | | 1DPC 2R | 120 Ω | Off | N/A | 60 Ω | Off | N/A | +------+---------+-------+--------+---------+-------+--------+---------+ | DDR4 | 1DPC 1R | 120 Ω | Off | Off | 80 Ω | Off | 240 Ω | | | 1DPC 2R | 120 Ω | Off | Off | 80 Ω | Off | 240 Ω | +------+---------+-------+--------+---------+-------+--------+---------+ ```
"Off" is equivalent to infinite resistance, although it is associated with the numerical value 0 in code (a 0-ohm resistor is a perfect cable, a short-circuit).
Mobile and ULT boards use "weaker" ODT settings to reduce power consumption, as they're usually battery-powered If power consumption is important on the Kontron bSL6, I'd recommend explicitly setting the board type to `BOARD_TYPE_MOBILE`.
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Angel Pons (Code Review)