[PATCH 2/3] drm: Warn if vblank state has become inconsistent.

[Mario Kleiner]

On Apr 27, 2011, at 10:58 AM, dri-devel-request at lists.freedesktop.org  
wrote:
> Message: 5
> Date: Wed, 27 Apr 2011 10:38:14 +0200
> From: Michel D?nzer <michel at daenzer.net>
> Subject: Re: [PATCH 2/3] drm: Warn if vblank state has become
> 	inconsistent.
> To: christopher.halse.rogers at canonical.com
> Cc: dri-devel at lists.freedesktop.org
> Message-ID: <1303893494.5633.129.camel at thor.local>
> Content-Type: text/plain; charset="UTF-8"
>
> On Mit, 2011-04-27 at 16:10 +1000,  
> christopher.halse.rogers at canonical.com wrote:
>> From: Christopher James Halse Rogers  
>> <christopher.halse.rogers at canonical.com>
>>
>> After emitting all the waiting vblank events no-one should hold
>> a vblank reference.  Emit a warning if this is not the case.
>>
>> Signed-off-by: Christopher James Halse Rogers  
>> <christopher.halse.rogers at canonical.com>
>> ---
>>  drivers/gpu/drm/drm_irq.c |    1 +
>>  1 files changed, 1 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
>> index a1f12cb..72407fa 100644
>> --- a/drivers/gpu/drm/drm_irq.c
>> +++ b/drivers/gpu/drm/drm_irq.c
>> @@ -960,6 +960,7 @@ void drm_vblank_off(struct drm_device *dev,  
>> int crtc)
>>  						 e->event.sequence);
>>  	}
>>
>> +	WARN_ON(atomic_read(&dev->vblank_refcount[crtc]) != 0);
>>  	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
>>  }
>>  EXPORT_SYMBOL(drm_vblank_off);
>
> Reviewed-by: Michel D?nzer <michel at daenzer.net>
>


Any pending kms pageflip will also hold a reference on the vblank of  
a crtc, so having the refcount non-zero there is not really a sign of  
inconsistency, so i'm not sure if a warning is appropriate there.

-mario

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Mario Kleiner
Max Planck Institute for Biological Cybernetics
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