linux-kernel - Re: [Intel-gfx] [3.14.0-rc4] regression: drm FIFO underruns

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Message-ID: <CADDKRnAhB2i1fKExPn3kAm_nX=PS1tf_YhasTHNCEHM6JatP5A@mail.gmail.com>
Date:	Fri, 16 May 2014 19:25:23 +0200
From:	Jörg Otte <jrg.otte@...il.com>
To:	Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:	Damien Lespiau <damien.lespiau@...el.com>,
	David Airlie <airlied@...ux.ie>,
	intel-gfx <intel-gfx@...ts.freedesktop.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Dave Airlie <airlied@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [Intel-gfx] [3.14.0-rc4] regression: drm FIFO underruns

2014-05-16 13:53 GMT+02:00 Ville Syrjälä <ville.syrjala@...ux.intel.com>:
> On Tue, May 13, 2014 at 06:38:32PM +0200, Daniel Vetter wrote:
>> On Tue, May 13, 2014 at 05:21:49PM +0200, Jörg Otte wrote:
>> > 2014-05-13 15:22 GMT+02:00 Daniel Vetter <daniel@...ll.ch>:
>> > > On Tue, May 13, 2014 at 12:38:41PM +0200, Daniel Vetter wrote:
>> > >> On Tue, May 13, 2014 at 12:29 PM, Jörg Otte <jrg.otte@...il.com> wrote:
>> > >> >>> Branch drm-intel-nightly as of
>> > >> >>> ed60c27 drm-intel-nightly: 2014y-05m-09d-21h-51m-45s integration manifest
>> > >> >>> looks badly:
>> > >> >>>    - KDE splash screen on boot-up is not visible
>> > >> >>>    - x-windows don't have title and menu bars
>> > >> >>>    - KDE system menu is not visible
>> > >> >>>    - moving windows around destroys its content
>> > >> >>
>> > >> >> Ugh, that's ugly. Nothing else change like e.g. the version of
>> > >> >> xfree-video-intel?
>> > >> >
>> > >> >  (II) Loading /usr/lib/xorg/modules/drivers/intel_drv.so
>> > >> >  (II) Module intel: vendor="X.Org Foundation"
>> > >> >  compiled for 1.11.3, module version = 2.17.0
>> > >> >  Module class: X.Org Video Driver
>> > >> >  ABI class: X.Org Video Driver, version 11.0
>> > >>
>> > >> Chris, any ideas? It's an ivybridge apparently.
>> > >>
>> > >> For the fifo underruns I think we've fully confirmed that they only
>> > >> happen on boot-up. I'll try to come up with some ideas what could have
>> > >> gone wrong there.
>> > >
>> > > Please test the below patch.
>> > > -Daniel
>> > >
>> > > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
>> > > index b10fbde1d5ee..63ced2dee027 100644
>> > > --- a/drivers/gpu/drm/i915/i915_irq.c
>> > > +++ b/drivers/gpu/drm/i915/i915_irq.c
>> > > @@ -427,9 +427,6 @@ bool __intel_set_cpu_fifo_underrun_reporting(struct drm_device *dev,
>> > >
>> > >         ret = !intel_crtc->cpu_fifo_underrun_disabled;
>> > >
>> > > -       if (enable == ret)
>> > > -               goto done;
>> > > -
>> > >         intel_crtc->cpu_fifo_underrun_disabled = !enable;
>> > >
>> > >         if (enable && (INTEL_INFO(dev)->gen < 5 || IS_VALLEYVIEW(dev)))
>> > > @@ -441,7 +438,6 @@ bool __intel_set_cpu_fifo_underrun_reporting(struct drm_device *dev,
>> > >         else if (IS_GEN8(dev))
>> > >                 broadwell_set_fifo_underrun_reporting(dev, pipe, enable);
>> > >
>> > > -done:
>> > >         return ret;
>> > >  }
>> > >
>> > > --
>> >
>> > Doesn't work for me, I still have an underrun at boot-up.
>>
>> I'm at a loss tbh with ideas. We successfully disable both pipes, then
>> enable pipe A and it all works.
>>
>> Then we enable pipe B and _both_ pipes underrun immediately afterwards.
>> Really strange. Can you please reproduce the issue again on
>> drm-intel-nightly (latest -nightly should also have the display
>> corruptions fixed, so good to retest anyway) and attach a new dmesg with
>> drm.debug=0xe.
>
> I see a few underrun on my IVB as well. But it seems to be limited to
> cases that involve the VGA connector, which doesn't actually exist on
> this machine so I can't be sure if it's really properly set up on the
> PCH. But so far with just two HDMI connectors I was unable to reproduce
> it.
>
>>
>> Meanwhile I'll try to come up with new theories and ideas.
>
> I was thinking that we might frob with the PCH refclk during driver init
> and that might cause the PCH underrun for Jörg, but it looks like the
> underruns really happen at the modeset time which is much later than the
> PCH refclock init.
>
> For the 1<->n pipe transition, I don't think we handle it correctly at
> the moment. I have a fix as part of my remaining watermark patches. I
> rebased those and I'll repost them soon. In the meantime I pushed them
> to [1]. Jörg, can you give that branch a go?
>
> [1] git://gitorious.org/vsyrjala/linux.git watermarks_intm_31_notrace
>
Unfortunately not working for me.
It gives me some more errors:

[drm:ivybridge_set_fifo_underrun_reporting] *ERROR* uncleared fifo
underrun on pipe A
[drm:ivb_err_int_handler] *ERROR* Pipe A FIFO underrun
[drm:ivybridge_set_fifo_underrun_reporting] *ERROR* uncleared fifo
underrun on pipe B
[drm:ivb_err_int_handler] *ERROR* Pipe B FIFO underrun
[drm:cpt_set_fifo_underrun_reporting] *ERROR* uncleared pch fifo
underrun on pch transcoder A
[drm:cpt_serr_int_handler] *ERROR* PCH transcoder A FIFO underrun
[drm:cpt_set_fifo_underrun_reporting] *ERROR* uncleared pch fifo
underrun on pch transcoder B
[drm:cpt_serr_int_handler] *ERROR* PCH transcoder B FIFO underrun

Thanks, Jörg
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