[PATCH 13/15] vmwgfx: Add a get_vblank_counter function

[Thomas Hellstrom]

On 09/28/2010 09:23 AM, Michel Dänzer wrote:
> On Mon, 2010-09-27 at 15:20 +0200, Thomas Hellstrom wrote:
>    
>> Avoids an oops during drm_irq_uninstall.
>>      
> Why not fix the oops instead of providing dummy hooks to work around it?
>
>
>    
This is because the vblank system in DRM appears unconditional. You 
can't choose not to enable it, because then you'd hit uninitialized 
values during various ioctls and drm_irq_uninstall.

Simply testing for presence of the get_vblank_counter function before 
calling it would mean providing the dummy hook in core drm instead of 
the driver...

A correct fix would require making the vblank system optional, and isn't 
a trivial task, so I figured better to put that on the to-do list and 
fix the oops now.

/Thomas