linux-kernel - Re: [git pull] drm merge for 3.9-rc1

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Date:	Wed, 27 Feb 2013 13:30:07 +1000
From:	Dave Airlie <airlied@...il.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Dave Airlie <airlied@...ux.ie>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Imre Deak <imre.deak@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	DRI mailing list <dri-devel@...ts.freedesktop.org>
Subject: Re: [git pull] drm merge for 3.9-rc1

On Wed, Feb 27, 2013 at 11:39 AM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> On Mon, Feb 25, 2013 at 4:05 PM, Dave Airlie <airlied@...ux.ie> wrote:
>>
>> Highlights:
>>
>> i915: all over the map, haswell power well enhancements, valleyview macro horrors cleaned up, killing lots of legacy GTT
>> code,
>
> Lowlight:
>
> There's something wrong with i915 DP detection or whatever. I get
> stuff like this:
>
> [    5.710827] [drm:intel_dp_aux_wait_done] *ERROR* dp aux hw did not
> signal timeout (has irq: 1)!
> [    5.720810] [drm:intel_dp_aux_wait_done] *ERROR* dp aux hw did not
> signal timeout (has irq: 1)!
> [    5.730794] [drm:intel_dp_aux_wait_done] *ERROR* dp aux hw did not
> signal timeout (has irq: 1)!
> [    5.740782] [drm:intel_dp_aux_wait_done] *ERROR* dp aux hw did not
> signal timeout (has irq: 1)!
> [    5.750775] [drm:intel_dp_aux_wait_done] *ERROR* dp aux hw did not
> signal timeout (has irq: 1)!
> [    5.750778] [drm:intel_dp_aux_ch] *ERROR* dp_aux_ch not done status
> 0xa145003f
> .....
> [    8.149931] [drm:intel_dp_aux_ch] *ERROR* dp_aux_ch not done status
> 0xa145003f
>
> and after that the screen ends up black.
>
> It's happened twice now, but is not 100% repeatable. It looks like the
> message itself is new,  but the black screen is also new and does seem
> to happen when I get the message, so...
>
> The second time I touched the power button, and the machine came back.
> Apparently the suspend/resume cycle made it all magically work: the
> suspend caused the same errors, but then the resume made it all good
> again.
>
> Some kind of missed initialization at bootup? It's not reliable enough
> to bisect, but I obviously suspect commit 9ee32fea5fe8 ("drm/i915:
> irq-drive the dp aux communication") since that is where the message
> was added..
>
> Btw, looking at that commit, what do you think the semantics of the
> timeout in something like
>
>     done = wait_event_timeout(dev_priv->gmbus_wait_queue, C, 10);
>
> would be? What's that magic "10"? It's some totally random number.
>
> Guys, it should be something meaningful. If you meant a tenth of a
> second, use HZ/10 or something. Because just the plain "10" is crazy.
> I happen to have CONFIG_HZ_1000=y, and you're apparently waiting for a
> hundreth of a second. Was that what you intended? Because if it was,
> it is still crap, since CONFIG_HZ might be 100, and then you're
> waiting for ten times longer.

Yeah the looks bogus, Daniel and Imre fail, though I think Daniel is
on holiday this week,
so maybe if you can make it revert, that might be the best option,

If you want to just bump it so Ironlake isn't affected, (patch attached).

Is this external DP monitor or eDP laptop panel btw?

Dave.

Download attachment "0001-drm-i915-only-use-irq-for-dp-on-post-ilk.patch" of type "application/octet-stream" (999 bytes)