[Intel-gfx] [PATCH 42/44] drm/i915: Defer enabling rc6 til after we submit the first batch/context

[Chris Wilson]

On Wed, Jun 15, 2016 at 01:18:27PM +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. As we do not forcibly load the kernel context at resume,
> we have to hook into the batch submission to be sure that the render
> state is setup before enabling rc6.
> 
> However, since we don't enable powersaving until that first batch, we
> queued a delayed task in order to guarantee that the batch is indeed
> submitted.
> 
> v2: Rearrange intel_disable_gt_powersave() to match.
> v3: Apply user specified cur_freq (or idle_freq if not set).
> v4: Give in, and supply a delayed work to autoenable rc6
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala at intel.com>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>

Mika, you complained about this, does this address your needs?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre