[Intel-gfx] [PATCH 4/4] drm/i915: optional fewer warning patch

[Ben Widawsky]

On Sat, Apr 09, 2011 at 11:31:14PM +0100, Chris Wilson wrote:
> On Sat,  9 Apr 2011 13:31:22 -0700, Ben Widawsky <ben at bwidawsk.net> wrote:
> > +	 *
> > +	 * Intelligent users of the interface may do a force_wake_get() followed
> > +	 * by many register reads and writes, knowing that the reference count
> > +	 * is already incremented. So we do not want to warn on those.
> >  	 */
> 
> Hmm, any place where we touch registers without holding a lock, unless
> under exceptional conditions such as !SYSTEM_RUNNING, is a bug waiting to
> happen. And probably already happened. Nasty, hard to reproduce race
> conditions.

The only use I had in mind was doing a bunch of reads, or perhaps
polling on a register. I didn't have a specific case but it seemed
feasible in certain cases.

> -Chris

Ben