Re: [PATCH] drm/vblank: Use u32 consistently for vblank counters

From: Thierry Reding <thierry.reding@gmail.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Daniel Vetter" <daniel.vetter@intel.com>,
	"Intel Graphics Development" <intel-gfx@lists.freedesktop.org>,
	"Michel Dänzer" <michel@daenzer.net>,
	"DRI Development" <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH] drm/vblank: Use u32 consistently for vblank counters
Date: Fri, 7 Aug 2015 13:56:37 +0200	[thread overview]
Message-ID: <20150807115636.GA24471@ulmo> (raw)
In-Reply-To: <1438943477-23537-1-git-send-email-daniel.vetter@ffwll.ch>


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On Fri, Aug 07, 2015 at 12:31:17PM +0200, Daniel Vetter wrote:
> In
> 
> 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(-)

Reviewed-by: Thierry Reding <treding@nvidia.com>

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