Re: [PATCH v12 4/7] drm/i915/skl: Update plane watermarks atomically during plane updates

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From	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v12 4/7] drm/i915/skl: Update plane watermarks atomically during plane updates
Date	Mon, 22 Aug 2016 13:30:01 +0200
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Op 17-08-16 om 21:55 schreef Lyude:
> Thanks to Ville for suggesting this as a potential solution to pipe
> underruns on Skylake.
>
> On Skylake all of the registers for configuring planes, including the
> registers for configuring their watermarks, are double buffered. New
> values written to them won't take effect until said registers are
> "armed", which is done by writing to the PLANE_SURF (or in the case of
> cursor planes, the CURBASE register) register.
>
> With this in mind, up until now we've been updating watermarks on skl
> like this:
This patch breaks on plane disabling. I think that all the disable_plane hooks
should zero all the watermark values. This might also make modeset more reliable

It's shown in this testcase that I wrote to expose this issue: kms_atomic_transition.plane-all-modeset-transition

I've applied patch 1, 2, 3 and 5 with some minor fixes.

Thread

[PATCH v12 4/7] drm/i915/skl: Update plane watermarks atomically during plane updates Lyude <cpaul@redhat.com> - 2016-08-17 22:00 +0200
  Re: [PATCH v12 4/7] drm/i915/skl: Update plane watermarks atomically  during plane updates Maarten Lankhorst <maarten.lankhorst@linux.intel.com> - 2016-08-22 13:30 +0200
    [PATCH v13 4/7] drm/i915/skl: Update plane watermarks atomically during plane updates Lyude <cpaul@redhat.com> - 2016-08-22 19:00 +0200
      Re: [PATCH v13 4/7] drm/i915/skl: Update plane watermarks atomically  during plane updates Maarten Lankhorst <maarten.lankhorst@linux.intel.com> - 2016-08-23 12:20 +0200
        [RESEND PATCH v13 7/7] drm/i915/skl: Update DDB values atomically with wms/plane attrs Lyude <cpaul@redhat.com> - 2016-08-23 16:20 +0200
        [RESEND PATCH v13 6/7] drm/i915: Move CRTC updating in atomic_commit into it's own hook Lyude <cpaul@redhat.com> - 2016-08-23 16:20 +0200

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