Hi Nico,
just a quick, hopefully encouraging data point: I tested your Alder
Lake-N libgfxinit work on a real Alder Lake-N board and it brings up a
native coreboot boot picture - no GOP blob involved.
Board: BKHD / Topton 1264NP-12-4L (Intel N100, Alder Lake-N), which I'm
upstreaming right now (CB:93713, currently NO_GFX_INIT until ADL-N
libgfxinit lands).
Setup: your libgfxinit ADL-N branch (the tip around c640977 - "Turn Alder
Lake into its own generation", the power-domain / CDClk-when-firmware-left-
the-PLL-disabled / DBUF bits) together with the coupled coreboot side
(GFX_GMA_GENERATION = "Alderlake"; without it libgfxinit aborts with
"Incompatible CPU or PCH").
Result on the hardware:
* rear HDMI (combo PHY, "HDMI2") lights up with a coreboot framebuffer,
* the soldered DP++ port driven as HDMI over TC1 (HDMI_TC1) also lights
up and reads EDID over GMBUS.
Both come up purely via libgfxinit, no FSP GOP / IntelGopDriver.
For context: I had independently been working on the ADL-N light-up at the
same time, on the current coreboot libgfxinit branch, and arrived at the same
conclusions - e.g. the dedicated CDClk PLL (CDCLK_PLL_ENABLE) left disabled
by the IoT FSP so the pipe ran off the ~19.2 MHz bypass clock, the per-pipe
power wells, and the plane DBUF allocation. It was reassuring to converge on
exactly the same root causes; your series already had all of it and
generally in cleaner shape, so I've happily dropped my own patches in favour
of yours.
So from where I sit the ADL-N enablement already works end to end on N100
silicon. If it helps, I'm happy to:
* rebase/test future revisions of the series on this board and report
back / give Tested-by,
* keep the board available as an ADL-N test platform.
Is there anything still blocking the series, or anything I can do to help
it along (review, testing, the coreboot-side GFX_GMA_GENERATION glue)? I'd
like to follow up with a libgfxinit-enabled version of the board once it
lands, so even a rough sense of the plan would help me time that - no
pressure at all
Thanks a lot for the ADL-N work!
Cheers,
Sebastian
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