From: "Michel Dänzer" <michel@daenzer.net>
To: dri-devel@lists.freedesktop.org
Subject: [PATCH] drm: Don't pass negative delta to ktime_sub_ns()
Date: Wed, 12 Jun 2013 11:58:44 +0200 [thread overview]
Message-ID: <1371031124-8867-1-git-send-email-michel@daenzer.net> (raw)
From: Michel Dänzer <michel.daenzer@amd.com>
It takes an unsigned value. This happens not to blow up on 64-bit
architectures, but it does on 32-bit, causing
drm_calc_vbltimestamp_from_scanoutpos() to calculate totally bogus
timestamps for vblank events. Which in turn causes e.g. gnome-shell to
hang after a DPMS off cycle with current xf86-video-ati Git.
Cc: stable@vger.kernel.org
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
---
drivers/gpu/drm/drm_irq.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index a6a8643..39665f8 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -708,7 +708,10 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
/* Subtract time delta from raw timestamp to get final
* vblank_time timestamp for end of vblank.
*/
- etime = ktime_sub_ns(etime, delta_ns);
+ if (delta_ns < 0)
+ etime = ktime_add_ns(etime, -delta_ns);
+ else
+ etime = ktime_sub_ns(etime, delta_ns);
*vblank_time = ktime_to_timeval(etime);
DRM_DEBUG("crtc %d : v %d p(%d,%d)@ %ld.%ld -> %ld.%ld [e %d us, %d rep]\n",
--
1.8.3
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next reply other threads:[~2013-06-12 9:58 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-12 9:58 Michel Dänzer [this message]
2013-06-12 10:48 ` [PATCH] drm: Don't pass negative delta to ktime_sub_ns() Chris Wilson
2013-06-12 11:06 ` Chris Wilson
2013-06-12 10:50 ` Imre Deak
2013-06-13 7:40 ` Daniel Vetter
2013-07-17 11:58 ` Chris Wilson
2013-08-07 8:42 ` Michel Dänzer
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