[Bug 83759] [BSW Bisected]igt/kms_flip subcases cause "WARNING: CPU: 0 PID: 3785 at drivers/gpu/drm/i915/intel_display.c:3486 intel_crtc_wait_for_pending_flips+0xdd/0x197 [i915]()"

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=83759

Guo Jinxian <jinxianx.guo at intel.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|bisect_pending              |
            Summary|[BSW                        |[BSW Bisected]igt/kms_flip
                   |Regression]igt/kms_flip     |subcases cause "WARNING:
                   |subcases cause "WARNING:    |CPU: 0 PID: 3785 at
                   |CPU: 0 PID: 3785 at         |drivers/gpu/drm/i915/intel_
                   |drivers/gpu/drm/i915/intel_ |display.c:3486
                   |display.c:3486              |intel_crtc_wait_for_pending
                   |intel_crtc_wait_for_pending |_flips+0xdd/0x197 [i915]()"
                   |_flips+0xdd/0x197 [i915]()" |

--- Comment #1 from Guo Jinxian <jinxianx.guo at intel.com> ---
e17ac6db2ef99388b750b2141c11974dc5742913 is the first bad commit 
commit e17ac6db2ef99388b750b2141c11974dc5742913 
Author: Ville Syrjälä <ville.syrjala at linux.intel.com> 
AuthorDate: Thu Oct 9 19:37:15 2014 +0300 
Commit: Jani Nikula <jani.nikula at intel.com> 
CommitDate: Thu Oct 16 14:58:44 2014 +0300 

drm/i915: Don't trust the DP_DETECT bit for eDP ports on CHV 

On CHV the display DDC pins may be muxed to an alternate function if 
there's no need for DDC on a specific port, which is the case for eDP 
ports since there's no way to plug in a DP++ HDMI dongle. 

This causes problems when trying to determine if the port is present 
since the the DP_DETECTED bit is the latched state of the DDC SDA pin 
at boot. If the DDC pins are muxed to an alternate function the bit 
may indicate that the port isn't present. 

To work around this look at the VBT as well as the DP_DETECTED bit 
to determine if we should attempt registering an eDP port. Do this 
only for ports B and C since port D doesn't support eDP (no PPS/BLC). 

In theory someone could also wire up a normal DP port w/o DDC lines. 
That would just mean that simple DP++ HDMI dongles wouldn't work 
on such a port. With this change we would still fail to register 
such DP ports. But let's hope no one wires their board in such a way, 
and if they do we can extend the VBT checks to cover normal DP ports 
as well. 

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84265 
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com> 
Reviewed-by: Damien Lespiau <damien.lespiau at intel.com> 
Signed-off-by: Jani Nikula <jani.nikula at intel.com> 

:040000 040000 0b768aac5e80cee20320cf387f0a9dab0c9f4cf8
581bee5771f0039afb5db5ede0540876e7d9b0ee M drivers

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