Re: [PATCH v2 for -fixes] drm/i915: Disable stolen memory when DMAR is active

From: Jani Nikula <jani.nikula@intel.com>
To: David Woodhouse <dwmw2@infradead.org>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH v2 for -fixes] drm/i915: Disable stolen memory when DMAR is active
Date: Thu, 20 Mar 2014 11:23:43 +0200	[thread overview]
Message-ID: <87siqdw7ds.fsf@intel.com> (raw)
In-Reply-To: <1395301759.19007.66.camel@shinybook.infradead.org>

On Thu, 20 Mar 2014, David Woodhouse <dwmw2@infradead.org> wrote:
> On Thu, 2014-03-20 at 09:36 +0200, Jani Nikula wrote:
>> 
>> Or an additional knob, in case it's really not working and people want
>> to get other things depending on prelim hw support done.
>
> Yeah. Perhaps the best answer is a 'disable_silicon_workarounds' option,
> to disable *all* workarounds for silicon bugs. Couple that with a printk
> telling the user that workarounds are disabled *and* VT-d is enabled.
>
> That's a nice simple thing for the chipset validation folks to be
> looking for. Unless they see that and have no issues with either
> framebuffer or X, the chipset hasn't been tested.
>
> That aside, I'm also unhappy with your patch on general principles. As a
> rule I'd like to see references to a *specific* published erratum, for
> anything we disable. Otherwise we're just admitting that life is too
> hard and we *never* bother to test our silicon before we ship it and we
> *expect* it to be broken.
>
> If we chase broken hardware to the point where errata are published, we
> should hopefully ensure that the problem feeds back to the validation
> folks who haven't done their job properly. Every time.
>
> (Pondered making this an internal email, but hey — *you're* the one who
> said "our hardware is always broken and we don't even bother to track
> individual brokenness". I'm just translating it into English from what's
> in your patch :)

I'll have to dodge this particular discussion, just because it was
really Chris' patch which I merely repainted with colours requested by
our resident interior designer Daniel. ;)

BR,
Jani.

>
> -- 
> dwmw2
>
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-- 
Jani Nikula, Intel Open Source Technology Center
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