tree b69bfa9e71e46c8c7470cbdf49de8530227d6687
parent 8116188fdef5946bcbb2d73e41d7412a57ffb034
author Dave Airlie <airlied@redhat.com> 1275370344 +1000
committer Dave Airlie <airlied@redhat.com> 1304480326 +1000

vgaarb: use bridges to control VGA routing where possible.

So in a lot of modern systems, a GPU will always be below a parent bridge that won't share with any other GPUs. This means VGA arbitration on those GPUs can be controlled by using the bridge routing instead of io/mem decodes.

The problem is locating which GPUs share which upstream bridges. This patch attempts to identify all the GPUs which can be controlled via bridges, and ones that can't. This patch endeavours to work out the bridge sharing semantics.

When disabling GPUs via a bridge, it doesn't do irq callbacks or touch the io/mem decodes for the gpu.

Signed-off-by: Dave Airlie <airlied@redhat.com>