Quoting Dhinakaran Pandiyan (2018-02-16 04:33:19)
> From: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
>
> So far we are using frontbuffer tracking for everything
> and ignoring that PSR has a HW capable HW tracking for many
> modern usages of GPU on Core platforms and newer Atom ones.
>
> One reason for that is that we were trying to keep same
> infrastructure in place for VLV/CHV than the rest of platforms.
> But also because when this infrastructure was created
> the front-buffer-tracking origin wasn't that good and stable
> how it is today after Paulo reworked it to attend FBC cases.
>
> However this PSR implementation without HW tracking died
> on gen8LP. And newer platforms are starting to demand more HW
> tracking specially with PSR2 cases in mind.
>
> By disabling and re-enabling PSR totally every time we believe
> someone is going to change the front buffer content we don't
> allow PSR HW tracking to do this job and specially compromising
> the whole idea of PSR2 case where the HW tracking detect only
> the damaged area and do a partial screen update.
>
> So, from now on, on the platforms that has hw_tracking let's
> rely more on HW tracking.
>
> This also is the case in used by other drivers and more validated
> by SV teams. So I hope that this will lead us to less misterious
> bugs.
>
> v2: Only do this for platform that actually has hw tracking.
>
> v3 from DK
> Do this only for flips, small gradual changes are better.
>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
> Cc: Jim Bride <jim.bride@xxxxxxxxxxxxxxx>
> Cc: Vathsala Nagaraju <vathsala.nagaraju@xxxxxxxxx>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_drv.h | 1 +
> drivers/gpu/drm/i915/intel_drv.h | 3 ++-
> drivers/gpu/drm/i915/intel_frontbuffer.c | 2 +-
> drivers/gpu/drm/i915/intel_psr.c | 10 +++++++++-
> 4 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 90eca42ab2b8..31aae988d515 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -770,6 +770,7 @@ struct i915_psr {
> bool y_cord_support;
> bool colorimetry_support;
> bool alpm;
> + bool has_hw_tracking;
Time for some bool:1 compaction?
> @@ -841,6 +842,9 @@ void intel_psr_invalidate(struct drm_i915_private *dev_priv,
> if (!CAN_PSR(dev_priv))
> return;
>
> + if (dev_priv->psr.has_hw_tracking && origin == ORIGIN_FLIP)
> + return;
> +
> mutex_lock(&dev_priv->psr.lock);
> if (!dev_priv->psr.enabled) {
> mutex_unlock(&dev_priv->psr.lock);
> @@ -881,6 +885,9 @@ void intel_psr_flush(struct drm_i915_private *dev_priv,
> if (!CAN_PSR(dev_priv))
> return;
>
> + if (dev_priv->psr.has_hw_tracking && origin == ORIGIN_FLIP)
> + return;
> +
Much easier for the causal reader to understand :)
-Chris
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