[RFC PATCH v2] xfree86: add a -gpu switch to select primary gpu

[Alexander E. Patrakov]

2013/6/21 Maarten Lankhorst <maarten.lankhorst at canonical.com>:
> For the open source drivers there should be a different way to do so, try
> running this before starting X:
>
> if [ -f /sys/kernel/debug/vgaswitcheroo/switch]; then
>   echo DIS > /sys/kernel/debug/vgaswitcheroo/switch
>   echo ON > /sys/kernel/debug/vgaswitcheroo/switch
> fi

According to https://help.ubuntu.com/community/HybridGraphics:

echo DIS > /sys/kernel/debug/vgaswitcheroo/switch
Connects discrete graphics with outputs.

I assume this is for laptops that can dynamically switch their HDMI or
other outputs from one card to another. However, this is completely
different from what my Sony laptop provides. The cards and their
outputs are physically separate. The Intel card is in the laptop, and
can drive the internal panel, the VGA and the HDMI output. The Radeon
card is in the dock station, is always on (there is no ATPX method in
ACPI tables), works only from AC and has its own VGA and HDMI outputs,
also located on the dock station. So this laptop, when docked, can
drive five different displays, including the internal one. And I want
to connect the TV to the HDMI output in the dock station because it is
convenient (less cables attached to the side of the laptop itself).

As I am physically away from this laptop, I cannot check whether
vgaswitcheroo works (but assume it shouldn't).

--
Alexander E. Patrakov