[Intel-gfx] [PATCH 40/50] drm/i915/bdw: Handle context switch events

[Daniel Vetter]

On Wed, Jun 11, 2014 at 03:23:33PM +0000, Mateo Lozano, Oscar wrote:
> > > > - Ack the interrupt inmediately, before trying to handle it (fix for
> > > > missing interrupts by Bob Beckett <robert.beckett at intel.com>).
> > >
> > > This interrupt handling change is interesting since it might explain
> > > our irq handling woes on gen5+ with the two-level GT interrupt handling
> > scheme.
> > > Can you please roll this out as a prep patch for all the existing gt
> > > interrupt sources we handle already for gen5+?
> > >
> > > Thanks, Daniel
> > 
> > Can do.
> 
> One question, though: why only the GT interrupts? what about DE, PM, etc...?
> 
> It looks like the BSpec is pretty clear on this:
> 
> 1 - Disable Master Interrupt Control
> 2 - Find the category of interrupt that is pending
> 3 - Find the source(s) of the interrupt and ***clear the Interrupt Identity bits (IIR)***
> 4 - Process the interrupt(s) that had bits set in the IIRs
> 5 - Re-enable Master Interrupt Control

Yeah, makes sense to do it for all. When I've looked at it the funky part
are the SDE interrupts where we (at least on pre-bdw) have this crazy
hack. I guess at least that one we should leave in since apparently it
works.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch