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Re: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7 merge window

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  Re: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7  merge window Ville Syrjälä <ville.syrjala@linux.intel.com> - 2016-07-07 18:20 +0200
    Re: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7  merge window James Bottomley <James.Bottomley@HansenPartnership.com> - 2016-07-07 19:00 +0200
      Re: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7  merge window James Bottomley <James.Bottomley@HansenPartnership.com> - 2016-07-07 21:20 +0200
        Re: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7  merge window Ville Syrjälä <ville.syrjala@linux.intel.com> - 2016-07-08 12:20 +0200
          Re: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7  merge window James Bottomley <James.Bottomley@HansenPartnership.com> - 2016-07-08 17:00 +0200
            Re: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7  merge window Ville Syrjälä <ville.syrjala@intel.com> - 2016-07-08 19:00 +0200

#1438710 — Re: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7 merge window

On Tue, Jun 21, 2016 at 06:44:34PM +0300, Ville Syrjälä wrote:
> On Tue, Jun 21, 2016 at 09:53:15AM -0400, James Bottomley wrote:
> > On Mon, 2016-06-20 at 11:03 +0300, Jani Nikula wrote:
> > > Cc: Ville
> > > 
> > > On Mon, 20 Jun 2016, James Bottomley <
> > > James.Bottomley@HansenPartnership.com> wrote:
> > > > OK, my candidate bad commit is this one:
> > > > 
> > > > commit a05628195a0d9f3173dd9aa76f482aef692e46ee
> > > > Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > Date:   Mon Apr 11 10:23:51 2016 +0300
> > > > 
> > > >     drm/i915: Get panel_type from OpRegion panel details
> > > > 
> > > > After being more careful about waiting to identify flicker, this 
> > > > one seems to be the one the bisect finds.  I'm now running v4.7-rc3
> > > > with this one reverted and am currently seeing no flicker problems.
> > > >   It is, however, early days because the flicker can hide for long 
> > > > periods, so I 'll wait until Monday evening and a few reboots 
> > > > before declaring victory.
> > > 
> > > If that turns out to be the bad commit, it doesn't really surprise 
> > > me, and that in itself is depressing.
> > 
> > As far as I can tell, after running for a day with this reverted, this
> > is the problem.  The flicker hasn't appeared with it reverted.  It's
> > pretty noticeable with this commit included.
> 
> Hmm. The only difference I can see is low vs. normal vswing. Panel 0 has
> low, panel 2 has normal. So either the VBT or opregion is telling utter
> lies, or there's some other bug in our low vswing support.

I did a quick once over of out DDI vswing stuff and didn't find anything
too serious. There were some buglets in the iboost handling, but I'm not
very hopeful that fixing those would help with your machine.

Here's a branch anyway in case you want to give it a go:
git://github.com/vsyrjala/linux.git ddi_iboost_fixes

Actually, I think the only patch in there that might make a difference is
15d887855180 ("drm/i915: Fix iboost setting for DDI with 4 lanes on SKL")

-- 
Ville Syrjälä
Intel OTC

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#1438725

On Thu, 2016-07-07 at 19:14 +0300, Ville Syrjälä wrote:
> On Tue, Jun 21, 2016 at 06:44:34PM +0300, Ville Syrjälä wrote:
> > On Tue, Jun 21, 2016 at 09:53:15AM -0400, James Bottomley wrote:
> > > On Mon, 2016-06-20 at 11:03 +0300, Jani Nikula wrote:
> > > > Cc: Ville
> > > > 
> > > > On Mon, 20 Jun 2016, James Bottomley <
> > > > James.Bottomley@HansenPartnership.com> wrote:
> > > > > OK, my candidate bad commit is this one:
> > > > > 
> > > > > commit a05628195a0d9f3173dd9aa76f482aef692e46ee
> > > > > Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > > Date:   Mon Apr 11 10:23:51 2016 +0300
> > > > > 
> > > > >     drm/i915: Get panel_type from OpRegion panel details
> > > > > 
> > > > > After being more careful about waiting to identify flicker, 
> > > > > this one seems to be the one the bisect finds.  I'm now 
> > > > > running v4.7-rc3 with this one reverted and am currently 
> > > > > seeing no flicker problems.   It is, however, early days 
> > > > > because the flicker can hide for long periods, so I 'll wait 
> > > > > until Monday evening and a few reboots before declaring
> > > > > victory.
> > > > 
> > > > If that turns out to be the bad commit, it doesn't really 
> > > > surprise me, and that in itself is depressing.
> > > 
> > > As far as I can tell, after running for a day with this reverted, 
> > > this is the problem.  The flicker hasn't appeared with it 
> > > reverted.  It's pretty noticeable with this commit included.
> > 
> > Hmm. The only difference I can see is low vs. normal vswing. Panel 
> > 0 has low, panel 2 has normal. So either the VBT or opregion is 
> > telling utter lies, or there's some other bug in our low vswing
> > support.
> 
> I did a quick once over of out DDI vswing stuff and didn't find 
> anything too serious. There were some buglets in the iboost handling, 
> but I'm not very hopeful that fixing those would help with your 
> machine. 
> 
> Here's a branch anyway in case you want to give it a go:
> git://github.com/vsyrjala/linux.git ddi_iboost_fixes
> 
> Actually, I think the only patch in there that might make a 
> difference is 15d887855180 ("drm/i915: Fix iboost setting for DDI 
> with 4 lanes on SKL")

Running with it now (the entire branch).  So far it looks OK, but I'll
give it a couple of days to see if anything manifests before declaring
victory.

James

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#1438910

On Thu, 2016-07-07 at 09:55 -0700, James Bottomley wrote:
> On Thu, 2016-07-07 at 19:14 +0300, Ville Syrjälä wrote:
> > On Tue, Jun 21, 2016 at 06:44:34PM +0300, Ville Syrjälä wrote:
> > > On Tue, Jun 21, 2016 at 09:53:15AM -0400, James Bottomley wrote:
> > > > On Mon, 2016-06-20 at 11:03 +0300, Jani Nikula wrote:
> > > > > Cc: Ville
> > > > > 
> > > > > On Mon, 20 Jun 2016, James Bottomley <
> > > > > James.Bottomley@HansenPartnership.com> wrote:
> > > > > > OK, my candidate bad commit is this one:
> > > > > > 
> > > > > > commit a05628195a0d9f3173dd9aa76f482aef692e46ee
> > > > > > Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > > > Date:   Mon Apr 11 10:23:51 2016 +0300
> > > > > > 
> > > > > >     drm/i915: Get panel_type from OpRegion panel details
> > > > > > 
> > > > > > After being more careful about waiting to identify flicker,
> > > > > > this one seems to be the one the bisect finds.  I'm now 
> > > > > > running v4.7-rc3 with this one reverted and am currently 
> > > > > > seeing no flicker problems.   It is, however, early days 
> > > > > > because the flicker can hide for long periods, so I 'll
> > > > > > wait 
> > > > > > until Monday evening and a few reboots before declaring
> > > > > > victory.
> > > > > 
> > > > > If that turns out to be the bad commit, it doesn't really 
> > > > > surprise me, and that in itself is depressing.
> > > > 
> > > > As far as I can tell, after running for a day with this
> > > > reverted, 
> > > > this is the problem.  The flicker hasn't appeared with it 
> > > > reverted.  It's pretty noticeable with this commit included.
> > > 
> > > Hmm. The only difference I can see is low vs. normal vswing.
> > > Panel 
> > > 0 has low, panel 2 has normal. So either the VBT or opregion is 
> > > telling utter lies, or there's some other bug in our low vswing
> > > support.
> > 
> > I did a quick once over of out DDI vswing stuff and didn't find 
> > anything too serious. There were some buglets in the iboost
> > handling, 
> > but I'm not very hopeful that fixing those would help with your 
> > machine. 
> > 
> > Here's a branch anyway in case you want to give it a go:
> > git://github.com/vsyrjala/linux.git ddi_iboost_fixes
> > 
> > Actually, I think the only patch in there that might make a 
> > difference is 15d887855180 ("drm/i915: Fix iboost setting for DDI 
> > with 4 lanes on SKL")
> 
> Running with it now (the entire branch).  So far it looks OK, but 
> I'll give it a couple of days to see if anything manifests before
> declaring victory.

Bad news, I'm afraid: after a couple of hours of run time, there is now
noticeable flicker on the display, so although the iboost fixes may
have lessened it, it's still present.

James

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#1439276

On Thu, Jul 07, 2016 at 12:19:36PM -0700, James Bottomley wrote:
> On Thu, 2016-07-07 at 09:55 -0700, James Bottomley wrote:
> > On Thu, 2016-07-07 at 19:14 +0300, Ville Syrjälä wrote:
> > > On Tue, Jun 21, 2016 at 06:44:34PM +0300, Ville Syrjälä wrote:
> > > > On Tue, Jun 21, 2016 at 09:53:15AM -0400, James Bottomley wrote:
> > > > > On Mon, 2016-06-20 at 11:03 +0300, Jani Nikula wrote:
> > > > > > Cc: Ville
> > > > > > 
> > > > > > On Mon, 20 Jun 2016, James Bottomley <
> > > > > > James.Bottomley@HansenPartnership.com> wrote:
> > > > > > > OK, my candidate bad commit is this one:
> > > > > > > 
> > > > > > > commit a05628195a0d9f3173dd9aa76f482aef692e46ee
> > > > > > > Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > > > > Date:   Mon Apr 11 10:23:51 2016 +0300
> > > > > > > 
> > > > > > >     drm/i915: Get panel_type from OpRegion panel details
> > > > > > > 
> > > > > > > After being more careful about waiting to identify flicker,
> > > > > > > this one seems to be the one the bisect finds.  I'm now 
> > > > > > > running v4.7-rc3 with this one reverted and am currently 
> > > > > > > seeing no flicker problems.   It is, however, early days 
> > > > > > > because the flicker can hide for long periods, so I 'll
> > > > > > > wait 
> > > > > > > until Monday evening and a few reboots before declaring
> > > > > > > victory.
> > > > > > 
> > > > > > If that turns out to be the bad commit, it doesn't really 
> > > > > > surprise me, and that in itself is depressing.
> > > > > 
> > > > > As far as I can tell, after running for a day with this
> > > > > reverted, 
> > > > > this is the problem.  The flicker hasn't appeared with it 
> > > > > reverted.  It's pretty noticeable with this commit included.
> > > > 
> > > > Hmm. The only difference I can see is low vs. normal vswing.
> > > > Panel 
> > > > 0 has low, panel 2 has normal. So either the VBT or opregion is 
> > > > telling utter lies, or there's some other bug in our low vswing
> > > > support.
> > > 
> > > I did a quick once over of out DDI vswing stuff and didn't find 
> > > anything too serious. There were some buglets in the iboost
> > > handling, 
> > > but I'm not very hopeful that fixing those would help with your 
> > > machine. 
> > > 
> > > Here's a branch anyway in case you want to give it a go:
> > > git://github.com/vsyrjala/linux.git ddi_iboost_fixes
> > > 
> > > Actually, I think the only patch in there that might make a 
> > > difference is 15d887855180 ("drm/i915: Fix iboost setting for DDI 
> > > with 4 lanes on SKL")
> > 
> > Running with it now (the entire branch).  So far it looks OK, but 
> > I'll give it a couple of days to see if anything manifests before
> > declaring victory.
> 
> Bad news, I'm afraid: after a couple of hours of run time, there is now
> noticeable flicker on the display, so although the iboost fixes may
> have lessened it, it's still present.

Oh well, I suspected as much. Which BIOS version did you have exactly?
If I'm reading the Dell website correctly there's a new one (1.4.4)
released on Jun 30, which is after you reported the issue. Might be
I'm reading the wrong thing though. Can you double check this?

-- 
Ville Syrjälä
Intel OTC

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#1439546

On Fri, 2016-07-08 at 13:19 +0300, Ville Syrjälä wrote:
> On Thu, Jul 07, 2016 at 12:19:36PM -0700, James Bottomley wrote:
> > On Thu, 2016-07-07 at 09:55 -0700, James Bottomley wrote:
> > > On Thu, 2016-07-07 at 19:14 +0300, Ville Syrjälä wrote:
> > > > On Tue, Jun 21, 2016 at 06:44:34PM +0300, Ville Syrjälä wrote:
> > > > > On Tue, Jun 21, 2016 at 09:53:15AM -0400, James Bottomley
> > > > > wrote:
> > > > > > On Mon, 2016-06-20 at 11:03 +0300, Jani Nikula wrote:
> > > > > > > Cc: Ville
> > > > > > > 
> > > > > > > On Mon, 20 Jun 2016, James Bottomley <
> > > > > > > James.Bottomley@HansenPartnership.com> wrote:
> > > > > > > > OK, my candidate bad commit is this one:
> > > > > > > > 
> > > > > > > > commit a05628195a0d9f3173dd9aa76f482aef692e46ee
> > > > > > > > Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > > > > > Date:   Mon Apr 11 10:23:51 2016 +0300
> > > > > > > > 
> > > > > > > >     drm/i915: Get panel_type from OpRegion panel
> > > > > > > > details
> > > > > > > > 
> > > > > > > > After being more careful about waiting to identify
> > > > > > > > flicker,
> > > > > > > > this one seems to be the one the bisect finds.  I'm now
> > > > > > > > running v4.7-rc3 with this one reverted and am
> > > > > > > > currently 
> > > > > > > > seeing no flicker problems.   It is, however, early
> > > > > > > > days 
> > > > > > > > because the flicker can hide for long periods, so I 'll
> > > > > > > > wait 
> > > > > > > > until Monday evening and a few reboots before declaring
> > > > > > > > victory.
> > > > > > > 
> > > > > > > If that turns out to be the bad commit, it doesn't really
> > > > > > > surprise me, and that in itself is depressing.
> > > > > > 
> > > > > > As far as I can tell, after running for a day with this
> > > > > > reverted, 
> > > > > > this is the problem.  The flicker hasn't appeared with it 
> > > > > > reverted.  It's pretty noticeable with this commit
> > > > > > included.
> > > > > 
> > > > > Hmm. The only difference I can see is low vs. normal vswing.
> > > > > Panel 
> > > > > 0 has low, panel 2 has normal. So either the VBT or opregion
> > > > > is 
> > > > > telling utter lies, or there's some other bug in our low
> > > > > vswing
> > > > > support.
> > > > 
> > > > I did a quick once over of out DDI vswing stuff and didn't find
> > > > anything too serious. There were some buglets in the iboost
> > > > handling, 
> > > > but I'm not very hopeful that fixing those would help with your
> > > > machine. 
> > > > 
> > > > Here's a branch anyway in case you want to give it a go:
> > > > git://github.com/vsyrjala/linux.git ddi_iboost_fixes
> > > > 
> > > > Actually, I think the only patch in there that might make a 
> > > > difference is 15d887855180 ("drm/i915: Fix iboost setting for
> > > > DDI 
> > > > with 4 lanes on SKL")
> > > 
> > > Running with it now (the entire branch).  So far it looks OK, but
> > > I'll give it a couple of days to see if anything manifests before
> > > declaring victory.
> > 
> > Bad news, I'm afraid: after a couple of hours of run time, there is
> > now
> > noticeable flicker on the display, so although the iboost fixes may
> > have lessened it, it's still present.
> 
> Oh well, I suspected as much. Which BIOS version did you have 
> exactly?

As mentioned upthread, now 1.4.3 since skylake microcode was
potentially implicated in the problem:

http://mid.gmane.org/1466179729.2271.33.camel@HansenPartnership.com

> If I'm reading the Dell website correctly there's a new one (1.4.4)
> released on Jun 30, which is after you reported the issue. Might be
> I'm reading the wrong thing though. Can you double check this?

New bios doesn't change the microcode:

[    2.390172] microcode: CPU0 sig=0x406e3, pf=0x80, revision=0x8a

And the flicker is still present.

James

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#1439680

On Fri, Jul 08, 2016 at 07:48:29AM -0700, James Bottomley wrote:
> On Fri, 2016-07-08 at 13:19 +0300, Ville Syrjälä wrote:
> > On Thu, Jul 07, 2016 at 12:19:36PM -0700, James Bottomley wrote:
> > > On Thu, 2016-07-07 at 09:55 -0700, James Bottomley wrote:
> > > > On Thu, 2016-07-07 at 19:14 +0300, Ville Syrjälä wrote:
> > > > > On Tue, Jun 21, 2016 at 06:44:34PM +0300, Ville Syrjälä wrote:
> > > > > > On Tue, Jun 21, 2016 at 09:53:15AM -0400, James Bottomley
> > > > > > wrote:
> > > > > > > On Mon, 2016-06-20 at 11:03 +0300, Jani Nikula wrote:
> > > > > > > > Cc: Ville
> > > > > > > > 
> > > > > > > > On Mon, 20 Jun 2016, James Bottomley <
> > > > > > > > James.Bottomley@HansenPartnership.com> wrote:
> > > > > > > > > OK, my candidate bad commit is this one:
> > > > > > > > > 
> > > > > > > > > commit a05628195a0d9f3173dd9aa76f482aef692e46ee
> > > > > > > > > Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > > > > > > Date:   Mon Apr 11 10:23:51 2016 +0300
> > > > > > > > > 
> > > > > > > > >     drm/i915: Get panel_type from OpRegion panel
> > > > > > > > > details
> > > > > > > > > 
> > > > > > > > > After being more careful about waiting to identify
> > > > > > > > > flicker,
> > > > > > > > > this one seems to be the one the bisect finds.  I'm now
> > > > > > > > > running v4.7-rc3 with this one reverted and am
> > > > > > > > > currently 
> > > > > > > > > seeing no flicker problems.   It is, however, early
> > > > > > > > > days 
> > > > > > > > > because the flicker can hide for long periods, so I 'll
> > > > > > > > > wait 
> > > > > > > > > until Monday evening and a few reboots before declaring
> > > > > > > > > victory.
> > > > > > > > 
> > > > > > > > If that turns out to be the bad commit, it doesn't really
> > > > > > > > surprise me, and that in itself is depressing.
> > > > > > > 
> > > > > > > As far as I can tell, after running for a day with this
> > > > > > > reverted, 
> > > > > > > this is the problem.  The flicker hasn't appeared with it 
> > > > > > > reverted.  It's pretty noticeable with this commit
> > > > > > > included.
> > > > > > 
> > > > > > Hmm. The only difference I can see is low vs. normal vswing.
> > > > > > Panel 
> > > > > > 0 has low, panel 2 has normal. So either the VBT or opregion
> > > > > > is 
> > > > > > telling utter lies, or there's some other bug in our low
> > > > > > vswing
> > > > > > support.
> > > > > 
> > > > > I did a quick once over of out DDI vswing stuff and didn't find
> > > > > anything too serious. There were some buglets in the iboost
> > > > > handling, 
> > > > > but I'm not very hopeful that fixing those would help with your
> > > > > machine. 
> > > > > 
> > > > > Here's a branch anyway in case you want to give it a go:
> > > > > git://github.com/vsyrjala/linux.git ddi_iboost_fixes
> > > > > 
> > > > > Actually, I think the only patch in there that might make a 
> > > > > difference is 15d887855180 ("drm/i915: Fix iboost setting for
> > > > > DDI 
> > > > > with 4 lanes on SKL")
> > > > 
> > > > Running with it now (the entire branch).  So far it looks OK, but
> > > > I'll give it a couple of days to see if anything manifests before
> > > > declaring victory.
> > > 
> > > Bad news, I'm afraid: after a couple of hours of run time, there is
> > > now
> > > noticeable flicker on the display, so although the iboost fixes may
> > > have lessened it, it's still present.
> > 
> > Oh well, I suspected as much. Which BIOS version did you have 
> > exactly?
> 
> As mentioned upthread, now 1.4.3 since skylake microcode was
> potentially implicated in the problem:
> 
> http://mid.gmane.org/1466179729.2271.33.camel@HansenPartnership.com
> 
> > If I'm reading the Dell website correctly there's a new one (1.4.4)
> > released on Jun 30, which is after you reported the issue. Might be
> > I'm reading the wrong thing though. Can you double check this?
> 
> New bios doesn't change the microcode:
> 
> [    2.390172] microcode: CPU0 sig=0x406e3, pf=0x80, revision=0x8a

I was hoping it would have fixed the VBT, but seems that was not the case
if the symptoms didn't change :(

-- 
Ville Syrjälä
Intel OTC
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