Resume from suspend broken in 3.15. (bisected)

[Ken Moffat <zarniwhoop@ntlworld.com>]

Hi Daniel,

 I've only started full testing of 3.15 on one of my machines now
that -rc7 has been released (this one had two issues in the radeon
code, second was fixed in rc7).  Unfortunately, suspend to RAM
(pm-suspend), or rather the wake-up, is broken on this box [ my
other two boxes are fine in rc7 ].

Bisection identified one of your commits -

commit 25f397a429dfa43f22c278d0119a60a343aa568f
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Fri Jul 19 18:57:11 2013 +0200

    drm/crtc-helper: explicit DPMS on after modeset
    
    Atm the crtc helper implementation of set_config has really
    inconsisten semantics: If just an fb update is good enough, dpms state
    will be left as-is, but if we do a full modeset we force everything to
    dpms on.
    
    This change has already been applied to the i915 modeset code in
    
('git show' stops at that point)


 I have attempted to revert this commit from Linus' current tree,
but git considered that there was a conflict, and I did not know how
to address it, so I aborted.  The conflict is :

<<<<<<< HEAD

                                if (connector->dpms != DRM_MODE_DPMS_ON) {
                                        DRM_DEBUG_KMS("connector dpms not on, full mode switch\n");
                                        mode_changed = true;
                                }

=======
>>>>>>> parent of 25f397a429df... drm/crtc-helper: explicit DPMS on
>>>>>>> after modeset
                                break;
                        }
                }


 The processor is an AMD A4 APU.  The symptoms after this commit are
that pm-suspend works (I invoke it from my keyboard's sleep key),
i.e. the power LED on the case goes out and the monitor goes black
and reports no signal.  When I press a key to resume, the power LED
comes on but the screen stays black.  Magic-SysRQ does not work and
I have to use the case switch to reboot.  That results in filesystem
errors which fsck fixes and warns about (probably, just a sign of
unclean shutdown).

 The only thing in the log are a couple of messages from EXT4 at the
end of putting the box to sleep -
May 28 16:19:02 bluesbreaker kernel: [   39.440859] EXT4-fs (sda10): re-mounted. Opts: commit=0
May 28 16:19:02 bluesbreaker kernel: [   39.592318] EXT4-fs (sda13): re-mounted. Opts: commit=0
May 28 16:20:05 bluesbreaker syslogd 1.5.0: restart.

 What can I do to help debug this ?

ĸen
-- 
Nanny Ogg usually went to bed early. After all, she was an old lady.
Sometimes she went to bed as early as 6 a.m.