linux-kernel - Re: [PATCH 02/21] drm/i915: Shut down PCH interrupts during irq

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Date:	Fri, 30 Sep 2011 19:56:14 +0200
From:	Daniel Vetter <daniel@...ll.ch>
To:	Keith Packard <keithp@...thp.com>
Cc:	Daniel Vetter <daniel@...ll.ch>, Dave Airlie <airlied@...hat.com>,
	intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 02/21] drm/i915: Shut down PCH interrupts during
 irq_uninstall

On Fri, Sep 30, 2011 at 10:44:22AM -0700, Keith Packard wrote:
> On Fri, 30 Sep 2011 18:20:48 +0200, Daniel Vetter <daniel@...ll.ch> wrote:
> 
> > Shouldn't we mask/ack south DE irqs before before we mask DE irqs to avoid
> > races, i.e.  move this new code up?
> 
> I don't know. What about the GT interrupts? I just stuck stuff at the
> bottom, figuring it would do the least harm...

Thinking this through again I don't see the race anymore. I've forgotten
that masking things in IMR also prevents stuff from showing up in IIR and
hence a SDE irq after clearing DE irqs can't leave garbage behind in
DEIIR. So no need to clear things in the order the irqs propagate, i.e.
SDE->DE->GT. For the patch:

Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
-- 
Daniel Vetter
Mail: daniel@...ll.ch
Mobile: +41 (0)79 365 57 48
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