[Intel-gfx] [PATCH] [VPG HSW-A] drm/i915: BUN vol4g[DevHSW] Vblank interrupt on disabled pipe

[Ville Syrjälä]

On Wed, Sep 04, 2013 at 05:14:02PM +0530, Sandeep Ramankutty wrote:
> This change is to comply with the BUN - Vblank interrupt on disabled pipe.
> BUN states - Do not unmask and enable a vertical blank interrupt on a pipe
> that is not enabled. Do not leave this interrupt enabled and unmasked after
> the associated pipe is disabled. If the vblank interrupt is unmasked and
> enabled on a disabled pipe it will block package C3, wasting power.

We mask the interrupt in IMR when we don't need it, but we do leave it
enabled in IER. Is that a problem on HSW? I'm guessing not, since
powertop is telling me that I'm currently reaching pc8 w/ displays off,
and pc7 w/ eDP on.

In any case the patch would be buggy since it has no locking around
DEIER RMW accesses. But since powertop is telling me everything is
already fine, we shouldn't need this patch anyway.

-- 
Ville Syrjälä
Intel OTC