[Intel-gfx] No VBT in OpRegion / Switching MBP Arrandale

Adam Jackson ajax at redhat.com
Mon Aug 30 16:34:10 CEST 2010


On Fri, 2010-08-27 at 12:19 +0200, Andreas Heider wrote:
> Hello everyone,
> at the moment i'm trying to get vga_switcheroo working on a 2010
> macbook pro. This laptop has two graphics cards, a dedicated nvidia
> one and an integrated intel arrandale chip. Switching is still pretty
> rough but it kind of works and it's possible to get the intel card
> connected to the display.

It would be interesting to know if there's a VBT on the machine at all
anywhere.  It might be hiding in an ACPI reserved or non-volatile
region; /proc/iomem will show you where those are, and you can scrape
them out of /dev/mem with clever use of dd(1).

Or, Apple might have decided to do their own thing, in which case it's
all much harder.

The dual-channel LVDS thing you mention in the next message is a fair
point.  We should be able to just look at the native panel mode timings
and _know_ whether it needs to be dual-channel.  I think the break
frequency is 112MHz, I'm sure the docs have the real number.

- ajax
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