[Intel-gfx] [PATCH v2 (rebased) 4/4] drm/i915: Add locking to pll updates, v2.

[Ander Conselvan De Oliveira]

On Wed, 2016-03-16 at 18:48 +0100, Maarten Lankhorst wrote:
> Op 16-03-16 om 17:19 schreef Ander Conselvan De Oliveira:
> > On Mon, 2016-03-14 at 09:27 +0100, Maarten Lankhorst wrote:
> > > With async modesets this is no longer protected with connection_mutex,
> > > so ensure that each pll has its own lock. The pll configuration state
> > > is still protected; it's only the pll updates that need locking against
> > > concurrency.
> > I think I need to look at your async branch, since I'm not really sure how
> > async
> > will work. But locking the individual plls might fail in SKL with the
> > current
> > code. The register DPLL_CTRL1 controls all 4 plls, and currently it is
> > updated
> > with a read-modify-write in the enable hook, so we can't update two plls
> > concurrently.
> > 
> Would making the dpll lock global help? I don't think in practice the locks
> will be contended much,
> it's not a performance sensitive path.

Yeah, I think that should be enough.

Ander