Re: [BUG][REGRESSION] mangled display since -rc1

[Martin Steigerwald]

Hello.

Am Montag, 7. November 2016, 16:34:35 CET schrieb Martin Kepplinger:
> Am 2016-11-07 um 09:24 schrieb Jani Nikula:
> > On Sun, 06 Nov 2016, Martin Kepplinger <martink@xxxxxxxxx> wrote:
> >> I did not file a bug in bugzilla yet. I haven't given up that we can fix
> >> this here before the release. I've ignored it the last few days though.
> > 
> > You say it like filing the bug report and having the bug fixed are
> > mutually exclusive things...
> > 
> > Pretty please? It's easier for us to direct folks at the bug, with
> > history and logs in one place. I realize only Daniel and me were Cc'd
> > here, not intel-gfx list.
> > 
> > Also, please double check your bisect. Not sure why the finger points at
> > i915 when the bisect points at iommu merge.
[â]
> Chris Clayton wrote off list and the mentioned patch fixes the problem
> for me too, as it does for others. I hope it make it's way into the tree
> soon:

With 4.9-rc4 I have corruptions that look like the ones reported in this 
thread.

I reported my finding on LKML thread about 3.9-rc4. And in Bugzilla in a bug 
report with an attachment that shows the same type of corruptions as here in 
this thread:

https://patchwork.freedesktop.org/patch/116808/

mentioned in the other bug report and the following LKML thread does not fix 
the issue for me:

Re: [REGRESSION] Linux 4.9-rc4: gfx glitches on Intel Sandybridge (was: Re: 
Linux 4.9-rc4)
https://lkml.org/lkml/2016/11/6/70

https://bugzilla.kernel.org/show_bug.cgi?id=177701#c4


In my case it looks like this:

https://martin-steigerwald.de/tmp/display-issues-with-kernel-4.9-rc4.png


 I have a busy week, so I wonÂt to any bisecting at the moment. I am happy to 
test another patch during breaks between holding the training, but please 
point me specifically to what patch to test. Thank you.


In general I am a bit confused about:

1) when do I use the bugtracker

2) when to just post on LKML

3) and which bugtracker to use? bugzilla.kernel.org versus the freedesktop one 
in this case. See:

http://lkml.iu.edu/hypermail/linux/kernel/1611.0/03126.html

4) how to determine whether a bug report matches my case or not. In that case 
its easy enough considering the screenshots.

(using this list archive as threading view in lkml.org seems broken)

This bug is already being discussed in three places right now, I bet it makes 
sense to settle on one place. IÂd opt for Bugzilla but I would like to use my 
MUA to access it for simple comments.

Thanks,
Martin

> -------- Weitergeleitete Nachricht --------
> Betreff: Fwd: Re: Redraw issues on i915 on 4.9-rc
> Datum: Mon, 7 Nov 2016 13:48:14 +0000
> Von: Chris Clayton <chris2553@xxxxxxxxxxxxxx>
> An: martink@xxxxxxxxx
> 
> Hi Martin.
> 
> 
> I can't contact you through LKML because I'm not subscribed, but I've
> been working with Chris Wilson, one of the Intel
> DRM developers to analyse and fix the corruption. We've got a patch that
> fixes it for me and Norbert who also reported
> the problem. The patch is at the bottom of this message.
> 
> Hope it helps.
> 
> Chris
> 
> 
> -------- Forwarded Message --------
> Subject: Re: Redraw issues on i915 on 4.9-rc
> Date: Mon, 7 Nov 2016 09:25:59 +0000
> From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> To: Chris Clayton <chris2553@xxxxxxxxxxxxxx>
> CC: Norbert Preining <preining@xxxxxxxx>
> 
> On Mon, Nov 07, 2016 at 09:16:38AM +0000, Chris Clayton wrote:
> > Hello again.
> > 
> > I wasn't at all happy about the last bisect I did, so I've run it
> 
> again and this time spent at least 30 minutes using my
> 
> > system before marking a kernel as good. I've also noticed that when I
> 
> boot a bad kernel, the graphics associated with
> 
> > three of my desktop icons do not get drawn, so that helps.
> > 
> > The outcome of the bisection is:
> > 
> > a61007a83a4671da77210790997d5c8c92ed87ea is the first bad commit
> > commit a61007a83a4671da77210790997d5c8c92ed87ea
> > Author: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > Date:   Thu Aug 18 17:17:02 2016 +0100
> > 
> >     drm/i915: Fix partial GGTT faulting
> 
> That's just the enabling patch, everything was meant to be in place by
> then.
> 
> Oh noes, care to try:
> 
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c
> b/drivers/gpu/drm/i915/i915_gem.c
> index c642385bb236..a52b40bbac6f 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1837,7 +1837,7 @@ int i915_gem_fault(struct vm_area_struct *area,
> struct vm_fault *vmf)
>                 /* Use a partial view if it is bigger than available
> space */
>                 chunk_size = MIN_CHUNK_PAGES;
>                 if (i915_gem_object_is_tiled(obj))
> -                       chunk_size = max(chunk_size, tile_row_pages(obj));
> +                       chunk_size = roundup(chunk_size,
> tile_row_pages(obj));
>                  memset(&view, 0, sizeof(view));
>                 view.type = I915_GGTT_VIEW_PARTIAL;


-- 
Martin