[SRU][Artful][PATCH 0/1] drm/i915/fbdev: Always forward hotplug events

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[SRU][Artful][PATCH 0/1] drm/i915/fbdev: Always forward hotplug events

Joseph Salisbury-3
BugLink: http://bugs.launchpad.net/bugs/1724911

== SRU Justification ==
The bug reporter states that after upgrading his laptop to Ubuntu 17.10, he was
unable to access gettys on any of the text-mode VTs on his system.

gdm3 is running on VT1, his user session is running on VT2. He could switch
between these. If he switched to VT3, the display retained the output of
his X session, and the text console with getty never appears.  Switching
back to VT2 works fine.

The same problem was occuring with either Wayland or X.

This bug is a regression in Artful introduced by mainline commit:
7581d5ca2bb ("drm/i915/fbdev: Check for existence of ifbdev->vma before operations").

It was first found that this bug was fixed in v4.14-rc1.  However, after a lengthy
"Reverse" bisect, the exact commit could not be identified.  This is because the
fix came in via a merge base.  A regular bisect was then done to identify commit
7581d5ca2bb as the offending commit that introduced the bug.  Using the file
that this commit touched, a "Reverse" bisect was done again between
7581d5ca2bb..v4.14-rc1.  This identified the following commit 88be58be886f as
the fix to this regression.
   

== Fix ==
commit 88be58be886f1215cc73dc8c273c985eecd7385c
Author: Daniel Vetter <[hidden email]>
Date:   Thu Jul 6 15:00:19 2017 +0200

    drm/i915/fbdev: Always forward hotplug events


== Regression Potential ==
This patch fixes a current regression and is a minor one-liner.

== Test Case ==
A test kernel was built with this patch and tested by the original bug reporter.
The bug reporter states the test kernel resolved the bug.


Daniel Vetter (1):
  drm/i915/fbdev: Always forward hotplug events

 drivers/gpu/drm/i915/intel_fbdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--
2.7.4


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[SRU][Artful][PATCH 1/1] drm/i915/fbdev: Always forward hotplug events

Joseph Salisbury-3
From: Daniel Vetter <[hidden email]>

BugLink: http://bugs.launchpad.net/bugs/1724911

With deferred fbdev setup we always need to forward hotplug events,
even if fbdev isn't fully set up yet. Otherwise the deferred setup
will neer happen.

Originally this check was added in

commit c45eb4fed12d278d3619f1904885bd0d7bcbf036 (tag: drm-intel-next-fixes-2016-08-05)
Author: Chris Wilson <[hidden email]>
Date:   Wed Jul 13 18:34:45 2016 +0100

    drm/i915/fbdev: Check for the framebuffer before use

But the specific case of the hotplug function blowing up was fixed in

commit 50c3dc970a09b3b60422a58934cc27a413288bab
Author: Daniel Vetter <[hidden email]>
Date:   Fri Jun 27 17:19:22 2014 +0200

    drm/fb-helper: Fix hpd vs. initial config races

Cc: Maarten Lankhorst <[hidden email]>
Cc: Mika Kuoppala <[hidden email]>
Cc: Chris Wilson <[hidden email]>
Reviewed-by: Maarten Lankhorst <[hidden email]>
Signed-off-by: Daniel Vetter <[hidden email]>
Link: http://patchwork.freedesktop.org/patch/msgid/20170706130023.28417-1-daniel.vetter@...
(cherry picked from commit 88be58be886f1215cc73dc8c273c985eecd7385c)
Signed-off-by: Steve Langasek <[hidden email]>
Signed-off-by: Joseph Salisbury <[hidden email]>
Reported-by: Steve Langasek <[hidden email]>
Tested-by: Steve Langasek <[hidden email]>
---
 drivers/gpu/drm/i915/intel_fbdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index 0c4cde6..ee1a5b9 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -813,7 +813,7 @@ void intel_fbdev_output_poll_changed(struct drm_device *dev)
 {
  struct intel_fbdev *ifbdev = to_i915(dev)->fbdev;
 
- if (ifbdev && ifbdev->vma)
+ if (ifbdev)
  drm_fb_helper_hotplug_event(&ifbdev->helper);
 }
 
--
2.7.4


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