hybrid-graphics-linux team mailing list archive
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Re: Possibility for switching Hardware MUX
On Sunday 07 October 2012 11:58:23 Michael wrote:
> in BIOS I have an option to select Graphics between switchable and
> discrete. When switching to discrete, the intel VGA controller
> disappears completely from lspci. This makes me thinking that there must
> be an additional hardware multiplexer in my machine??? Am I right, that
> those hardware MUXes are usually switched using ACPI? It would really be
> nice to find out, which ACPI command switches the MUX in either
> direction. Switching off the nvidia card already works even though i am
> using the proprietary driver, as the nouveau driver seems not to support
> my card good enough.
The Lenovo enterprise laptops (like the Thinkpad W520) have the same options
for choosing between discrete/integrated/optimus (and maybe even switchable
graphics, but I am not sure on that). These machines have a hardware
multiplexer I guess, otherwise it is not possible to provide those options.
ACPI is a subsystem that also communicates with the BIOS, but I doubt that you
can switch graphics on-the-fly.
> Attached you can find my DSDT, which might be interesting for your
> projects as well.
Please provide the raw acpidump output, there might be more relevant tables
like SSDT. Do it for the different BIOS settings, I have seen an Acer laptop
that shows different ACPI tables depending on whether the
discrete/integrated/optimus mode is in use.