Re: [PATCH] drm/i915: paper over missed irq issues with force wake vodoo

From: Keith Packard <keithp@keithp.com>
To: intel-gfx <intel-gfx@lists.freedesktop.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
	stable@kernel.org, Eugeni Dodonov <eugeni.dodonov@intel.com>
Subject: Re: [PATCH] drm/i915: paper over missed irq issues with force wake vodoo
Date: Fri, 06 Jan 2012 12:56:20 -0800	[thread overview]
Message-ID: <86vcooturv.fsf@sumi.keithp.com> (raw)
In-Reply-To: <1325695930-2524-1-git-send-email-daniel.vetter@ffwll.ch>

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On Wed,  4 Jan 2012 17:52:10 +0100, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:

> Two things seem to do the trick on my ivb machine here:
> - prevent the gt from powering down while waiting for seqno
>   notification interrupts by grabbing the force_wake in get_irq (and
>   dropping it in put_irq again).
> - ordering writes from the ring's CS by reading a CS register, ACTHD
>   seems to work.
> 
> Only the blt&bsd ring on ivb seem to be massively affected by this,
> but for paranoia do this dance also on the render ring and on snb
> (i.e. all gpus with forcewake).
> 
> Tested with Eric's glCopyPixels loop which without this patch scores a
> missed irq every few seconds.
> 
> This patch needs my forcewake rework to use a spinlock instead of
> dev->struct_mutex.

I've pushed these to the forcewake-spinlock branch in both my fdo and
kernel repositories. Please give that a try on IVB and SNB to make sure
things are working right.

I'd like to get these into master as well as being sent off to stable@
for 3.2.x

-- 
keith.packard@intel.com

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