drm/i915: fix long-standing SNB regression in power consumption after resume

Commit Message

Jesse Barnes July 16, 2013, 5:06 p.m. UTC

On Tue, 16 Jul 2013 11:34:25 +0400
Konstantin Khlebnikov <[e-mail]> wrote:
> I've tested that patch and it really works for me. If you want change
> something for other hardware or
> extend range where forcewake is held prease do it in a separate patch.
> This will be good for bisecting new bugs in the future.

Thanks a ton for finding this Konstantin, it puts us on the right
track.

Can I ask you to test this patch?  The theory is that having RC6
enabled messes with the initial programming sequence, so it's probably
best to just shut it off at init until we're done, rather than trying
to forcewake around everywhere we need it.

Thanks,

Patch

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_d
index 12ea1a9..9152cba 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9648,6 +9648,9 @@  static void i915_disable_vga(struct drm_device *dev)
 
 void intel_modeset_init_hw(struct drm_device *dev)
 {
+       /* BIOS often leaves RC6 enabled, but disable it for hw init */
+       intel_disable_gt_powersave(dev);
+
        intel_init_power_well(dev);
 
        intel_prepare_ddi(dev);