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authorMichel Dänzer <michel.daenzer@amd.com>2013-06-12 11:58:44 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-14 22:59:09 -0700
commitac4ae0b99e3d708e90fe39019601d2a91dff7011 (patch)
tree83af9908bf9b247e49fdd8b1791ddc7b4a4e59d5
parentaabfe27dfe71d29b9ac08790f1a0ca240c1264b6 (diff)
drm: Don't pass negative delta to ktime_sub_ns()
commit e91abf80a0998f326107874c88d549f94839f13c upstream. 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. [airlied: regression introduced in drm: use monotonic time in drm_calc_vbltimestamp_from_scanoutpos] Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=59339 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=59836 Tested-by: shui yangwei <yangweix.shui@intel.com> Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> Reviewed-by: Imre Deak <imre.deak@intel.com> Signed-off-by: Dave Airlie <airlied@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/gpu/drm/drm_irq.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 8bcce7866d3..f92da0a32f0 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",