From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [PATCH 16/16] drm/i915: Improve PSR debugfs output
Date: Wed, 18 Jun 2014 18:02:23 +0200
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To: Chris Wilson <chris@chris-wilson.co.uk>, Daniel Vetter <daniel.vetter@ffwll.ch>, Intel Graphics Development <intel-gfx@lists.freedesktop.org>
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On Wed, Jun 18, 2014 at 03:51:01PM +0100, Chris Wilson wrote:
> On Wed, Jun 18, 2014 at 01:59:17PM +0200, Daniel Vetter wrote:
> > Add busy_frontbuffer_bits and locking.
> > 
> > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> > ---
> >  drivers/gpu/drm/i915/i915_debugfs.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> > index 4818aff9e6d6..6c0413fd3d37 100644
> > --- a/drivers/gpu/drm/i915/i915_debugfs.c
> > +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> > @@ -1971,10 +1971,15 @@ static int i915_edp_psr_status(struct seq_file *m, void *data)
> >  
> >  	intel_runtime_pm_get(dev_priv);
> >  
> > +	mutex_lock(&dev_priv->psr.lock);
> 
> It's debugfs. Play nice and let the user interrupt us, just in case.

I agree with dev->struct_mutex since the gpu hangs often, but for general
hw features I think the backtrace is good enough and the simpler locking
better. Worst case you need to spawn a new terminal over ssh because the
first one is stuck ;-)
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch