[PATCH 2/5] drm: Add initial dnyamic power off feature

[Dave Airlie]

On Mon, Sep 10, 2012 at 9:07 PM, Alan Cox <alan at lxorguk.ukuu.org.uk> wrote:
> On Mon, 10 Sep 2012 14:31:52 +1000
> Dave Airlie <airlied at gmail.com> wrote:
>
>> From: Dave Airlie <airlied at redhat.com>
>>
>> For secondary GPUs in laptops, i.e. optimus or powerxpress, we have
>> methods for powering down the GPU completely. This adds support
>> to the drm core for powering back up the GPU on any access from
>> ioctls or sysfs interfaces, and fires a 5s timer to test if
>> we can power the GPU off.
>
>
> Is there a reason for basically re-inventing the existing Linux dynamic
> power management layer ?

Not really, wanted to have something simple to demo first. This

"bus type drivers of the buses the devices are on are
 responsible for the actual handling of the autosuspend requests and
 wake-up events."

seemed to imply there was some magic in the PCI bus layer that is
generic, and in this case that doesn't exist.

We have a 3 specific ACPI calls to power off the GPU slot for nvidia,
radeon and apple.

Dave.