[Intel-gfx] [PATCH 3/3] drm/i915: Try harder to disable trickle feed on VLV

[Chris Wilson]

On Tue, May 21, 2013 at 03:28:34PM +0300, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> The specs are a bit unclear whether the per-plane trickle feed disable
> control exists on VLV. There is another trickle feed disable control
> in the MI_ARB register.
> 
> Based on some quick register dumps from Jani's VLV machine, the per-plane
> bits don't actually seem to exist, so I'm guessing we should use the
> MI_ARB method instead.

I think neither. I'm guessing this behaviour is covered by 'Note: On
mobile products this bit will be ignored such that Trickle Feed is
always disabled.' in the DSP.CNTR spec. And I don't think MI_ARB_STATE
is applicable as it wasn't used for the display block VLV was based
upon.

Being VPN-less I can't actually dig through the VLV bspec to confirm.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre