Nico Huber has posted comments on this change. ( https://review.coreboot.org/29434 )
Change subject: mb/lenovo/x220: Add x1 as a variant ......................................................................
Patch Set 5: Code-Review-1
(1 comment)
Please use an override devicetree instead. See google/fizz for example, `config OVERRIDE_DEVICETREE` and 27efc501d1 (util/sconfig: Add support for overriding base tree properties/node).
https://review.coreboot.org/#/c/29434/5/src/mainboard/lenovo/x220/variants/x... File src/mainboard/lenovo/x220/variants/x1/devicetree.cb:
https://review.coreboot.org/#/c/29434/5/src/mainboard/lenovo/x220/variants/x... PS5, Line 79: 0x2005
As far as I understand UVSCC only applies to the "upper" aka second flash chip.
The SPI Guide suggests to fill both for maximum compatibility. And no, it's kind of the other way around. If there is no distinction, everything is "upper".
The actual distinction is not based on the chips but a configurable boundary (FPBA in the descriptor). Everything below that boundary is "lower"; if FPBA is 0, nothing is below it.
They probably made it that weird to be able to treat two flash chips with the same characteristics as one (wrt. all the lower/upper set- tings).