[Intel-gfx] [PATCH v2 1/3] drm/i915: Fix cdclk vs. dev_cdclk mess when not recomputing things

[Joseph Yasi]

On Thu, Nov 17, 2016 at 3:17 AM, Paul Bolle <pebolle at tiscali.nl> wrote:

> On Mon, 2016-11-14 at 18:35 +0200, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> >
> > When we end up not recomputing the cdclk, we need to populate
> > intel_state->cdclk with the "atomic_cdclk_freq" instead of the
> > current cdclk_freq. When no pipes are active, the actual cdclk_freq
> > may be lower than what the configuration of the planes and
> > pipes would require from the point of view of the software state.
> >
> > This fixes bogus WARNS from skl_max_scale() which is trying to check
> > the plane software state against the cdclk frequency. So any time
> > it got called during DPMS off for instance, we might have tripped
> > the warn if the current mode would have required a higher than
> > minimum cdclk.
> >
> > v2: Drop the dev_cdclk stuff (Maarten)
> >
> > Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> > Cc: Mika Kahola <mika.kahola at intel.com>
> > Cc: bruno.pagani at ens-lyon.org
> > Cc: Daniel J Blueman <daniel.blueman at gmail.com>
> > Cc: Paul Bolle <pebolle at tiscali.nl>
> > Cc: Joseph Yasi <joe.yasi at gmail.com>
> > Tested-by: Paul Bolle <pebolle at tiscali.nl> (v1)
>
> I've run v2 of this patch (on top of v4.8.8) for over a day now without
> hitting the WARN_ON_ONCE. Of course, my machine was suspended for large
> parts
> of that period. But still, the WARN_ON_ONCE used to be triggered much
> quicker.
> So in short: you can drop "(v1)" as I tested both versions now.
>
> By the way, the scary i915 *ERROR*s are gone now too, as are the visual
> glitches that accompanied those *ERROR*s. Apparently the v4.8.y series
> picked
> up a few fixes. Those made i915 a much better experience. Nice!
>
> > Tested-by: Joseph Yasi <joe.yasi at gmail.com> (v1)
>

I've also applied this patch (and the other two in the series) on top of
4.8.8. I haven't hit the WARN_ON_ONCE with the patches either.

The flickering I was experiencing earlier turned out to be due to a
motherboard failure. Replacing the motherboard fixed that problem.


> > Cc: stable at vger.kernel.org
> > Fixes: 1a617b77658e ("drm/i915: Keep track of the cdclk as if all crtc's
> were active.")
>
> (I seem to remember discussing the reasons why a v4.6 bug was first
> noticed on
> v4.8. I haven't looked into that yet. By now it's unlikely I ever will.
> Sorry
> about that.)
>
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98214
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>
> Thanks,
>
>
> Paul Bolle
>
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