[Intel-gfx] i915 irq storm mitigation in 3.10

[Egbert Eich]

Jan Niggemann writes:
 > Hi Daniel,
 > 
 > Am 25.07.2013 11:58, schrieb Daniel Vetter:
 > > Can you pls try the below
 > > patch (on top of Egbert's debug stuff)?
 > >
 > > diff --git a/drivers/gpu/drm/i915/i915_reg.h
 > > b/drivers/gpu/drm/i915/i915_reg.h
 > > index 6caa748..2d4c884 100644
 > > --- a/drivers/gpu/drm/i915/i915_reg.h
 > > +++ b/drivers/gpu/drm/i915/i915_reg.h
 > > @@ -1925,9 +1925,9 @@
 > >
 > >  #define PORT_HOTPLUG_STAT      (dev_priv->info->display_mmio_offset
 > > + 0x61114)
 > >  /* HDMI/DP bits are gen4+ */
 > > -#define   PORTB_HOTPLUG_LIVE_STATUS               (1 << 29)
 > > +#define   PORTD_HOTPLUG_LIVE_STATUS               (1 << 29)
 > >  #define   PORTC_HOTPLUG_LIVE_STATUS               (1 << 28)
 > > -#define   PORTD_HOTPLUG_LIVE_STATUS               (1 << 27)
 > > +#define   PORTB_HOTPLUG_LIVE_STATUS               (1 << 27)
 > >  #define   PORTD_HOTPLUG_INT_STATUS             (3 << 21)
 > >  #define   PORTC_HOTPLUG_INT_STATUS             (3 << 19)
 > >  #define   PORTB_HOTPLUG_INT_STATUS             (3 << 17)
 > I did, here are the logs:
 > 364K http://files.hz6.de/kern_20130724_2.log

I get a 'forbidden' when I try to access this.

 > I don't understand what exactly this patch does, but I noticed:
 > - much less drm debug info, resulting in a much smaller log
 > - no more noticeable lag on my system (even though a storm was 
 > detected).

Ok, so this indicates that the storm detection works now :)

 > I double checked the latter and the lag seems indeed to be gone...

Before we actually masked out individual events it was irrelevant
if the bits were mixed up. Now we need to be correct on these.

Jan, thanks for your help!

Cheers,
	Egbert.