nvidia "discrete" laptops - mine now works!

[matthew green <mrg%eterna23.net@localhost>]

hi folks.


i have a thinkpad P51 that i call my "big laptop", though it's starting
to get old now (i bought mine mid-2018).  it came with an nvidia GPU as
"discrete" graphics, but it never worked for me.  nouveau(4) never was
able to find the vbios and it thus failed during attach, and this meant
that the hdmi/dp/etc ports were unavailable as these were only connected
to the nvidia gpu, not the cpu (i915) gpu.

sometime between december last year and august this year, this was fixed
and i am now able to run X with nouveau when i configure the bios to be
"discrete".

i had spent a while trying to figure this out several years aog and the
debug messages still exist for that tree, and it seems that one of the
vbios search methods now works (slightly edited):

  nvbios_shadow:232: method [name=<none>]
  nvbios_shadow:232: method [name=PRAMIN]
  nvbios_shadow:232: method [name=PROM]
  nvbios_shadow:232: method [name=ACPI]
  nvbios_shadow:232: method [name=ACPI]
  nvbios_shadow:232: method [name=PCIROM]
  nvbios_shadow:232: method [name=PLATFORM]
  nouveau0: bios: version 84.06.76.00.15

where as previously this would look like:

  nvbios_shadow:232: method [name=<none>]
  nvbios_shadow:232: method [name=PRAMIN]
  nvbios_shadow:232: method [name=PROM]
  nvbios_shadow:232: method [name=ACPI]
  nvbios_shadow:232: method [name=ACPI]
  nvbios_shadow:232: method [name=PCIROM]
  nvbios_shadow:232: method [name=PLATFORM]
  shadow_method:133: init gave err -19
  nouveau0: autoconfiguration error: error: bios: unable to locate usable image
  nouveau0: autoconfiguration error: error: bios ctor failed, -22
  nouveau0: autoconfiguration error: unable to create nouveau device: 22
  
we still almost certainly need help to deal with multi-gpu control
of the display, what i understand is "drm prime", for this to work
nicely with "hybrid" as the setup, but at least for now i can finally
use the hdmi/dp ports on my laptop!

thanks most likely to Taylor but also to all who helped.
  
  
.mrg.