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From: Matt Roper <matthew.d.roper@intel.com>
To: "Chris Wilson" <chris@chris-wilson.co.uk>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Ville Syrjälä" <ville.syrjala@linux.intel.com>,
	"Jeremiah Mahler" <jmmahler@gmail.com>,
	"Jani Nikula" <jani.nikula@linux.intel.com>,
	"David Airlie" <airlied@linux.ie>,
	"Alex Deucher" <alexander.deucher@amd.com>,
	"Dave Airlie" <airlied@redhat.com>,
	"Ander Conselvan de Oliveira" <conselvan2@gmail.com>,
	linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org,
	dri-devel@lists.freedesktop.org
Subject: Re: [Intel-gfx] [BUG, bisect] drm/i915: mouse pointer lags and overshoots
Date: Mon, 19 Jan 2015 08:40:24 -0800	[thread overview]
Message-ID: <20150119164024.GI22549@intel.com> (raw)
In-Reply-To: <20150119110404.GA26577@nuc-i3427.alporthouse.com>

On Mon, Jan 19, 2015 at 11:04:04AM +0000, Chris Wilson wrote:
> On Mon, Jan 19, 2015 at 11:51:43AM +0100, Daniel Vetter wrote:
> > There's also an issue in (most) X drivers which exaberates this
> > issues: When changing the cursor buffer the X cursor code does a a)
> > disable cursor b) update cursor image c) enable cursor cycle.
> 
> Notably not -intel on which the bug has been observed. And more
> importantly, the slow downs don't seem to correlate with cursor change,
> just cursor movement.
> -Chris
> 
> -- 
> Chris Wilson, Intel Open Source Technology Centre

It seems that the simple fix for this case (movement only) is to just
skip the prepare_fb/cleanup_fb calls (and the associated vblank wait) in
the transitional plane helper when newfb == oldfb.  I just posted a
small patch that makes that change (and solves the cursor lag for me).

This won't solve the case if userspace uses a different framebuffer for
each update (while trying to update faster than the refresh rate).  Is
there any existing userspace that behaves this way that we can test
with?


Matt

-- 
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795

  reply	other threads:[~2015-01-19 16:40 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-17 10:06 Jeremiah Mahler
2015-01-18 13:57 ` Andrey Skvortsov
2015-01-19  9:08 ` [Intel-gfx] " Ville Syrjälä
2015-01-19 10:51   ` Daniel Vetter
2015-01-19 11:04     ` Chris Wilson
2015-01-19 16:40       ` Matt Roper [this message]
2015-01-19 20:43         ` Chris Wilson
2015-01-20  5:48         ` Daniel Vetter
2015-01-24  6:57           ` Jeremiah Mahler
2015-01-24 11:24             ` Daniel Vetter
2015-01-24 20:27               ` Jeremiah Mahler
2015-01-19 11:14     ` Ville Syrjälä

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