From: Michel Dänzer Date: Wed, 12 Jun 2013 09:58:44 +0000 (+0200) Subject: drm: Don't pass negative delta to ktime_sub_ns() X-Git-Tag: firefly_0821_release~6453^2~1089 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=ac4ae0b99e3d708e90fe39019601d2a91dff7011;p=firefly-linux-kernel-4.4.55.git 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 Signed-off-by: Michel Dänzer Reviewed-by: Imre Deak Signed-off-by: Dave Airlie Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 8bcce7866d36..f92da0a32f0d 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",