[Intel-gfx] [PATCH] drm/i915: On reset/suspend disable hpd pins & cancel pending delayed work

[Daniel Vetter]

On Fri, Sep 25, 2015 at 03:29:40PM +0300, Ville Syrjälä wrote:
> On Fri, Sep 25, 2015 at 08:09:57AM +0200, Egbert Eich wrote:
> > +void intel_hpd_uninit(struct drm_i915_private *dev_priv)
> > +{
> > +	struct drm_device *dev = dev_priv->dev;
> > +	int i;
> > +
> > +	cancel_delayed_work_sync(&dev_priv->hotplug.reenable_work);
> 
> What if another hpd happens here?
> 
> Oh and we already have the intel_hpd_cancel_work() function. Sounds like
> we need to rethink how that works rather than rolling another function
> to do the same thing.
> 
> There's also the matter of VLV/CHV where hpd init gets called from the
> display power well enable hook. I was thinking that could race with this
> stuff, but since this is only called from the suspend I suppose we
> shouldn't be re-enabling the display power well at that time.

At least on big core we have checks for intel_display_power_is_enabled in
the irq postinstall hooks and corresponding post_enable code in the power
well code to make sure you can enable interrupts/power wells in any order
and it'll work.

Not sure this is a reasonable design assumption any more, but otoh fixing
that will likely mean we need to fix the power well handling in our driver
load and suspend/resume code.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch