Re: [PATCH 3/3] drm/i915: use async hpd_irq_event function on resume

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, May 21, 2014 at 08:00:22AM -0700, Jesse Barnes wrote:
> On Wed, 21 May 2014 08:52:34 +0200
> Daniel Vetter <daniel@ffwll.ch> wrote:
> 
> > On Tue, May 20, 2014 at 03:25:35PM -0700, Jesse Barnes wrote:
> > > Gets the detect code (which may take awhile) out of the resume path,
> > > speeding things up a bit.
> > > 
> > > Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> > > ---
> > >  drivers/gpu/drm/i915/i915_drv.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> > > index 302495f..571f688 100644
> > > --- a/drivers/gpu/drm/i915/i915_drv.c
> > > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > > @@ -606,7 +606,7 @@ static int __i915_drm_thaw(struct drm_device *dev, bool restore_gtt_mappings)
> > >  		intel_hpd_init(dev);
> > >  		dev_priv->enable_hotplug_processing = true;
> > >  		/* Config may have changed between suspend and resume */
> > > -		drm_helper_hpd_irq_event(dev);
> > > +		async_schedule(drm_helper_hpd_irq_event_async, dev);
> > 
> > Does that really help all that much? I've thought the driver core
> > sychnronizes all the async workers again once resume is done. I'm better
> > to schedule this as a fully async work with e.g. a 1s delay, like we do
> > with the rps resume work.
> 
> That might be better, I'll check on the synchronization.  I thought
> async_schedule was the new hotness we were supposed to use everywhere...

It's pretty cool for easy async in driver load/resume since it autosyncs.
You can even create more async domains if you need finer-grained sync
points. But if we know that we can be more lenient than full sync before
our driver load/resume completes we need to use classical work queues.

But for stuff like doing paralle modeset restore async domains look like
the right thing.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch