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Re: Skylake graphics regression: projector failure with 4.8-rc3

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  Re: Skylake graphics regression: projector failure with 4.8-rc3 James Bottomley <James.Bottomley@HansenPartnership.com> - 2016-08-31 23:50 +0200
    Re: [Intel-gfx] Skylake graphics regression: projector failure with  4.8-rc3 "Zanoni, Paulo R" <paulo.r.zanoni@intel.com> - 2016-09-01 00:00 +0200
      Re: [Intel-gfx] Skylake graphics regression: projector failure with  4.8-rc3 James Bottomley <James.Bottomley@HansenPartnership.com> - 2016-09-01 00:30 +0200

#1473903 — Re: Skylake graphics regression: projector failure with 4.8-rc3

On Wed, 2016-08-31 at 11:23 -0700, James Bottomley wrote:
> On Fri, 2016-08-26 at 09:10 -0400, James Bottomley wrote:
> > We seem to have an xrandr regression with skylake now.  What's
> > happening is that I can get output on to a projector, but the 
> > system is losing video when I change the xrandr sessions (like 
> > going from a --above b to a --same-as b).  The main screen goes 
> > blank, which is basically a reboot situation.  Unfortunately, I 
> > can't seem to get the logs out of systemd to see if there was a 
> > dump to dmesg (the system was definitely responding).
> > 
> > I fell back to 4.6.2 which worked perfectly, so this is definitely 
> > some sort of regression.  I'll be able to debug more fully when I 
> > get back home from the Linux Security Summit.
> 
> I'm home now.  Unfortunately, my monitor isn't as problematic as the
> projector, but by flipping between various modes and separating and
> overlaying the panels with --above and --same-as (xrandr), I can
> eventually get it to the point where the main LCD panel goes black 
> and can only be restarted by specifying a different mode.
> 
> This seems to be associated with these lines in the X
> 
> [ 14714.389] (EE) intel(0): failed to set mode: Invalid argument [22]
> 
> But the curious thing is that even if this fails with the error 
> message once, it may succeed a second time, so it looks to be a 
> transient error translation problem from the kernel driver.
> 
> I've attached the full log below.
> 
> This is only with a VGA output.  I currently don't have a HDMI 
> dongle, but I'm in the process of acquiring one.

After more playing around, I'm getting thousands of these in the kernel
log (possibly millions: the log wraps very fast):

[23504.873606] [drm:intel_dp_start_link_train [i915]] *ERROR* failed to train DP, aborting

And then finally it gives up with 

[25023.770951] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun
[25561.926075] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun

And the crtc for the VGA output becomes non-responsive to any
configuration command.  This requires a reboot and sometimes a UEFI
variable reset before it comes back.

James

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#1473911 — Re: [Intel-gfx] Skylake graphics regression: projector failure with 4.8-rc3

Hi

Em Qua, 2016-08-31 às 14:43 -0700, James Bottomley escreveu:
> On Wed, 2016-08-31 at 11:23 -0700, James Bottomley wrote:
> > 
> > On Fri, 2016-08-26 at 09:10 -0400, James Bottomley wrote:
> > > 
> > > We seem to have an xrandr regression with skylake now.  What's
> > > happening is that I can get output on to a projector, but the 
> > > system is losing video when I change the xrandr sessions (like 
> > > going from a --above b to a --same-as b).  The main screen goes 
> > > blank, which is basically a reboot situation.  Unfortunately, I 
> > > can't seem to get the logs out of systemd to see if there was a 
> > > dump to dmesg (the system was definitely responding).
> > > 
> > > I fell back to 4.6.2 which worked perfectly, so this is
> > > definitely 
> > > some sort of regression.  I'll be able to debug more fully when
> > > I 
> > > get back home from the Linux Security Summit.
> > 
> > I'm home now.  Unfortunately, my monitor isn't as problematic as
> > the
> > projector, but by flipping between various modes and separating and
> > overlaying the panels with --above and --same-as (xrandr), I can
> > eventually get it to the point where the main LCD panel goes black 
> > and can only be restarted by specifying a different mode.
> > 
> > This seems to be associated with these lines in the X
> > 
> > [ 14714.389] (EE) intel(0): failed to set mode: Invalid argument
> > [22]
> > 
> > But the curious thing is that even if this fails with the error 
> > message once, it may succeed a second time, so it looks to be a 
> > transient error translation problem from the kernel driver.
> > 
> > I've attached the full log below.
> > 
> > This is only with a VGA output.  I currently don't have a HDMI 
> > dongle, but I'm in the process of acquiring one.
> 
> After more playing around, I'm getting thousands of these in the
> kernel
> log (possibly millions: the log wraps very fast):
> 
> [23504.873606] [drm:intel_dp_start_link_train [i915]] *ERROR* failed
> to train DP, aborting
> 
> And then finally it gives up with 
> 
> [25023.770951] [drm:intel_cpu_fifo_underrun_irq_handler [i915]]
> *ERROR* CPU pipe B FIFO underrun
> [25561.926075] [drm:intel_cpu_fifo_underrun_irq_handler [i915]]
> *ERROR* CPU pipe A FIFO underrun
> 
> And the crtc for the VGA output becomes non-responsive to any
> configuration command.  This requires a reboot and sometimes a UEFI
> variable reset before it comes back.

Please see this discussion:
https://patchwork.freedesktop.org/patch/103237/

Do you have this patch on your tree? Does the problem go away if you
revert it?

Thanks,
Paulo

> 
> James
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

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#1473935 — Re: [Intel-gfx] Skylake graphics regression: projector failure with 4.8-rc3

On Wed, 2016-08-31 at 21:51 +0000, Zanoni, Paulo R wrote:
> Hi
> 
> Em Qua, 2016-08-31 às 14:43 -0700, James Bottomley escreveu:
> > On Wed, 2016-08-31 at 11:23 -0700, James Bottomley wrote:
> > > 
> > > On Fri, 2016-08-26 at 09:10 -0400, James Bottomley wrote:
> > > > 
> > > > We seem to have an xrandr regression with skylake now.  What's
> > > > happening is that I can get output on to a projector, but the 
> > > > system is losing video when I change the xrandr sessions (like 
> > > > going from a --above b to a --same-as b).  The main screen goes
> > > > blank, which is basically a reboot situation.  Unfortunately, I
> > > > can't seem to get the logs out of systemd to see if there was a
> > > > dump to dmesg (the system was definitely responding).
> > > > 
> > > > I fell back to 4.6.2 which worked perfectly, so this is
> > > > definitely 
> > > > some sort of regression.  I'll be able to debug more fully when
> > > > I 
> > > > get back home from the Linux Security Summit.
> > > 
> > > I'm home now.  Unfortunately, my monitor isn't as problematic as
> > > the
> > > projector, but by flipping between various modes and separating
> > > and
> > > overlaying the panels with --above and --same-as (xrandr), I can
> > > eventually get it to the point where the main LCD panel goes
> > > black 
> > > and can only be restarted by specifying a different mode.
> > > 
> > > This seems to be associated with these lines in the X
> > > 
> > > [ 14714.389] (EE) intel(0): failed to set mode: Invalid argument
> > > [22]
> > > 
> > > But the curious thing is that even if this fails with the error 
> > > message once, it may succeed a second time, so it looks to be a 
> > > transient error translation problem from the kernel driver.
> > > 
> > > I've attached the full log below.
> > > 
> > > This is only with a VGA output.  I currently don't have a HDMI 
> > > dongle, but I'm in the process of acquiring one.
> > 
> > After more playing around, I'm getting thousands of these in the
> > kernel
> > log (possibly millions: the log wraps very fast):
> > 
> > [23504.873606] [drm:intel_dp_start_link_train [i915]] *ERROR*
> > failed
> > to train DP, aborting
> > 
> > And then finally it gives up with 
> > 
> > [25023.770951] [drm:intel_cpu_fifo_underrun_irq_handler [i915]]
> > *ERROR* CPU pipe B FIFO underrun
> > [25561.926075] [drm:intel_cpu_fifo_underrun_irq_handler [i915]]
> > *ERROR* CPU pipe A FIFO underrun
> > 
> > And the crtc for the VGA output becomes non-responsive to any
> > configuration command.  This requires a reboot and sometimes a UEFI
> > variable reset before it comes back.
> 
> Please see this discussion:
> https://patchwork.freedesktop.org/patch/103237/
> 
> Do you have this patch on your tree? Does the problem go away if you
> revert it?

Yes, I've got it, it went in in 4.8-rc3 according to git:

commit 58e311b09c319183254d9220c50a533e7157c9ab
Author: Matt Roper <matthew.d.roper@intel.com>
Date:   Thu Aug 4 14:08:00 2016 -0700

    drm/i915/gen9: Give one extra block per line for SKL plane WM
calculations

Reverting it causes the secondary display not to sync pretty much at
all.  However, in the flickers I can see, it does work OK and doesn't
now crash switching from --same-as to --above and back

I also still get the logs filling up with the link training errors.

On balance, although the behaviour is different, it's not an
improvement because if I can't sync with the projector, I can't really
use this as a fix.

James

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