From: Jesse Barnes <jbarnes@virtuousgeek.org>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 4/6] drm/i915: Disable FBC across page-flipping
Date: Thu, 7 Jul 2011 09:15:58 -0700 [thread overview]
Message-ID: <20110707091558.0b1963cd@jbarnes-desktop> (raw)
In-Reply-To: <1310039291-22554-5-git-send-email-chris@chris-wilson.co.uk>
On Thu, 7 Jul 2011 12:48:09 +0100
Chris Wilson <chris@chris-wilson.co.uk> wrote:
> Page-flipping updates the scanout address, nukes the FBC compressed
> image and so forces an FBC update so that the displayed image remains
> consistent. However, page-flipping does not update the FBC registers
> themselves, which remain pointing to both the old address and the old
> CPU fence. Future updates to the new front-buffer (scanout) are then
> undetected!
>
> This first approach to demonstrate the issue and highlight the fix,
> simply disables FBC upon page-flip (a recompression will be forced on
> every flip so FBC becomes immaterial) and then re-enables FBC in the
> page-flip finish work function, so that the FBC registers are now
> pointing to the new framebuffer and front-buffer rendering works once
> more.
>
> Ideally, we want to only re-enable FBC after page-flipping is complete,
> as otherwise we are just wasting cycles (along with an undesirable
> wait-for-vblank which will halve the frame-rate of vsync'ed games) and
> power (with needless recompression) whilst the page-flipping application
> is still running.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=33487
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
Yeah just disabling it is probably better than trying to let the hw
figure out what to recompress since it likely won't be worthwhile.
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
--
Jesse Barnes, Intel Open Source Technology Center
next prev parent reply other threads:[~2011-07-07 16:16 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-07 11:48 FBC fixes for review and testing Chris Wilson
2011-07-07 11:48 ` [PATCH 1/6] drm/i915: Remove vestigial pitch from post-gen2 FBC control routines Chris Wilson
2011-07-07 16:12 ` Jesse Barnes
2011-07-07 11:48 ` [PATCH 2/6] drm/i915: Use of a CPU fence is mandatory to update FBC regions upon CPU writes Chris Wilson
2011-07-07 16:13 ` Jesse Barnes
2011-07-07 11:48 ` [PATCH 3/6] drm/i915: Set persistent-mode for ILK/SNB framebuffer compression Chris Wilson
2011-07-07 16:14 ` Jesse Barnes
2011-07-07 11:48 ` [PATCH 4/6] drm/i915: Disable FBC across page-flipping Chris Wilson
2011-07-07 16:15 ` Jesse Barnes [this message]
2011-07-07 11:48 ` [PATCH 5/6] drm/i915: Only export the generic intel_disable_fbc() interface Chris Wilson
2011-07-07 16:16 ` Jesse Barnes
2011-07-07 17:19 ` [PATCH] drm/i915: Replace direct calls to vfunc.disable_fbc with intel_disable_fbc() Chris Wilson
2011-07-07 11:48 ` [PATCH 6/6] drm/i915: Perform intel_enable_fbc() from a delayed task Chris Wilson
2011-07-07 16:20 ` Jesse Barnes
2011-07-07 17:12 ` [PATCH] drm/i915: Flush any scheduled tasks during unload Chris Wilson
2011-07-07 15:45 ` FBC fixes for review and testing Keith Packard
2011-07-07 20:30 ` [PATCH] drm/i915: Share the common work of disabling active FBC before updating Chris Wilson
2011-07-07 20:52 ` Keith Packard
2011-07-07 21:14 ` Chris Wilson
2011-07-07 21:26 ` Keith Packard
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