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commit 99264a61dfcda41d86d0960cf2d4c0fc2758a773 Author: Daniel Vetter daniel.vetter@ffwll.ch Date: Wed Apr 15 19:34:43 2015 +0200

drm/vblank: Fixup and document timestamp update/read barriers

I've switched vblank->count from atomic_t to unsigned long and accidentally created an integer comparison bug in drm_vblank_count_and_time since vblanke->count might overflow the u32 local copy and hence the retry loop never succeed.

Fix this by consistently using u32.

Cc: Michel Dänzer michel@daenzer.net Reported-by: Michel Dänzer michel@daenzer.net Signed-off-by: Daniel Vetter daniel.vetter@intel.com --- drivers/gpu/drm/drm_irq.c | 2 +- include/drm/drmP.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index a7311c6e6f30..a2cfd2cc8c39 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -75,7 +75,7 @@ module_param_named(timestamp_precision_usec, drm_timestamp_precision, int, 0600) module_param_named(timestamp_monotonic, drm_timestamp_monotonic, int, 0600);

static void store_vblank(struct drm_device *dev, int crtc, - unsigned vblank_count_inc, + u32 vblank_count_inc, struct timeval *t_vblank) { struct drm_vblank_crtc *vblank = &dev->vblank[crtc]; diff --git a/include/drm/drmP.h b/include/drm/drmP.h index fdf8a501cb44..38e0e77d7277 100644 --- a/include/drm/drmP.h +++ b/include/drm/drmP.h @@ -691,7 +691,7 @@ struct drm_vblank_crtc { struct timer_list disable_timer; /* delayed disable timer */

/* vblank counter, protected by dev->vblank_time_lock for writes */ - unsigned long count; + u32 count; /* vblank timestamps, protected by dev->vblank_time_lock for writes */ struct timeval time[DRM_VBLANKTIME_RBSIZE];