From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ben Widawsky <ben@bwidawsk.net>
Subject: Re: [PATCH] drm/i915: tune down unknown unclaime write
 hsw debug message
Date: Fri, 11 Jan 2013 18:35:10 -0800
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To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Intel Graphics Development <intel-gfx@lists.freedesktop.org>
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On Tue, 8 Jan 2013 11:07:03 +0100
Daniel Vetter <daniel.vetter@ffwll.ch> wrote:

> On Tue, Jan 8, 2013 at 10:32 AM, Chris Wilson
> <chris@chris-wilson.co.uk> wrote:
> > On Tue,  8 Jan 2013 09:33:57 +0100, Daniel Vetter
> > <daniel.vetter@ffwll.ch> wrote:
> >> This could very well be caused by dirt left behind by the BIOS, so
> >> tune it down to the debug level.
> >
> > If the issue is solely the one described, then it should be silence
> > when we takeover, just like all the other error/debug status
> > registers.
> 
> Good point, I'll check whether pimping gt_reset is good enough.

I agree with Chris FWIW. Changing this for the sake of the one instance
during takeover isn't good enough.

> 
> > DRM_DEBUG is a little too noisy for this, maybe we should look at
> > trace_print or one of the other dynamic debugs for this class of
> > info?
> 
> The downside of trace_printk is that it doesn't pop up in dmesg. If
> all that reg checking starts to hurt, we might want to exclude the GT
> range from it - iirc this seemed most useful for display enabling.
> -Daniel

It was useful for display enabling because that's where the biggest
delta was for IVB->HSW. I don't think that it will be the case for all
platforms. The reason I found it interesting initially is it's also
capable of catching when we try to write to powered down things.