[Intel-gfx] [PATCH] drm/i915: Defer enabling rc6 til after we submit the first batch/context

[Chris Wilson]

On Wed, May 25, 2016 at 03:58:11PM +0100, Chris Wilson wrote:
> Some hardware requires a valid render context before it can initiate
> rc6 power gating of the GPU; the default state of the GPU is not
> sufficient and may lead to undefined behaviour. The first execution of
> any batch will load the "golden render state", at which point it is safe
> to enable rc6.

The big issue with first batch, is that it may not be RCS and so not
define the golden state and requires the user to do something for us to
save power.

The other approach is for the powersaving to send the batch itself if it
needs it.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre