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    SubjectRe: [git pull] drm fixes
    On Mon, 27 Feb 2012 13:33:53 -0300
    Eugeni Dodonov <eugeni@dodonov.net> wrote:

    > On Mon, Feb 27, 2012 at 13:09, Jesse Barnes <jbarnes@virtuousgeek.org>wrote:
    >
    > > On Thu, 23 Feb 2012 21:19:20 +0100
    > > Torsten Kaiser <just.for.lkml@googlemail.com> wrote:
    > >
    > > > On Wed, Feb 22, 2012 at 8:56 PM, Dave Airlie <airlied@linux.ie> wrote:
    > > > > Eugeni Dodonov (4):
    > > > > drm/i915: gen7: implement rczunit workaround
    > > > > drm/i915: gen7: Implement an L3 caching workaround.
    > > > > drm/i915: gen7: work around a system hang on IVB
    > > > > drm/i915: do not enable RC6p on Sandy Bridge
    > > >
    > > > That last patch about RC6p looks wrong.
    > > >
    > > > It does:
    > > > GEN6_RC_CTL_RC6_ENABLE |
    > > > (IS_GEN7(dev_priv->dev)) ? GEN6_RC_CTL_RC6p_ENABLE
    > > : 0;
    > > > But I think this was meant:
    > > > GEN6_RC_CTL_RC6_ENABLE |
    > > > ((IS_GEN7(dev_priv->dev)) ?
    > > GEN6_RC_CTL_RC6p_ENABLE : 0);
    > > >
    > > > Or did I get the operator precedence wrong?
    > >
    > > You're right, no cookie for Eugeni. :) This would have prevented RC6
    > > from ever getting enabled though, which should have the same effect as
    > > the patch intended, though at the cost of higher power consumption.
    > >
    >
    > Actually, no, it got RC6p enabled - so it got to have all the power savings
    > of RC6 plus some additional ones in the range of 0.1W, but it also resulted
    > in the very same problem as before, when both RC6 and RC6p were enabled.
    >
    > So, from what we've seen with
    > https://wiki.ubuntu.com/Kernel/PowerManagementRC6, the graphics corruptions
    > do only happen when RC6p is enabled (either together with RC6, or
    > individually, on its own). If we have only RC6, all the issues are gone so
    > far.
    >
    > So this bad patch had its use after all - it served to finally isolate and
    > prove that the i915_enable_rc6-related issues are caused directly by RC6p.

    Oh you're right; I had the bit positions mixed up... I thought the
    higher level bit toggled all RC6 functionality, but that's kept
    separate from this.

    --
    Jesse Barnes, Intel Open Source Technology Center
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