linux-kernel - Re: [Intel-gfx] [PATCH] drm/i915: fix long-standing SNB regression in power consumption after resume

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Date:	Tue, 16 Jul 2013 13:19:25 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
Cc:	Konstantin Khlebnikov <khlebnikov@...nvz.org>,
	David Airlie <airlied@...ux.ie>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	intel-gfx <intel-gfx@...ts.freedesktop.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	dri-devel <dri-devel@...ts.freedesktop.org>,
	Alexander Kaltsas <alexkaltsas@...il.com>,
	rocko <rockorequin@...mail.com>
Subject: Re: [Intel-gfx] [PATCH] drm/i915: fix long-standing SNB regression
 in power consumption after resume

On Tue, 16 Jul 2013 10:06:54 -0700
Jesse Barnes <jbarnes@...tuousgeek.org> wrote:

> On Tue, 16 Jul 2013 11:34:25 +0400
> Konstantin Khlebnikov <khlebnikov@...nvz.org> 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.

Oops, last one triggers a warn about IRQs.  This one doesn't and still
works for me.

Testing welcome.

Thanks,
-- 
Jesse Barnes, Intel Open Source Technology Center

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index c9d9d20..d962ec0 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4112,6 +4112,9 @@ i915_gem_init_hw(struct drm_device *dev)
        drm_i915_private_t *dev_priv = dev->dev_private;
        int ret;
 
+       /* BIOS often leaves RC6 enabled, but disable it for hw init */
+       intel_disable_gt_powersave(dev);
+
        if (INTEL_INFO(dev)->gen < 6 && !intel_enable_gtt())
                return -EIO;
 
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