[Bug 67043] Atombios stuck in a look during resume

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=67043

--- Comment #7 from Parag <parag.warudkar at gmail.com> ---
After a not-so-clean git bisect (compilation failures in vgacon.c, some TI
driver I didn't need) this was the result - at least it is related to drm.

git bisect good
372835a8527f85b3eff20a18c2c339e827dfd4e4 is the first bad commit
commit 372835a8527f85b3eff20a18c2c339e827dfd4e4
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date:   Sat Jun 15 00:13:13 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

    commit e3de42b68478a8c95dd27520e9adead2af9477a5
    Author: Imre Deak <imre.deak at intel.com>
    Date:   Fri May 3 19:44:07 2013 +0200

        drm/i915: force full modeset if the connector is in DPMS OFF mode

    which according to Greg KH seems to aim for a new record in most
    Bugzilla: links in a commit message.

    The history of this dpms forcing is pretty interesting. This patch
    here is an almost-revert of

    commit 811aaa55ba21ab37407018cfc01770d6b037d3fb
    Author: Keith Packard <keithp at keithp.com>
    Date:   Thu Feb 3 16:57:28 2011 -0800

        drm: Only set DPMS ON when actually configuring a mode

    which fixed the bug of trying to dpms on disabled outputs, but
    introduced the new discrepancy between an fb update only and full
    modesets. The actual introduction of this goes back to

    commit bf9dc102e284a5aa78c73fc9d72e11d5ccd8669f
    Author: Keith Packard <keithp at keithp.com>
    Date:   Fri Nov 26 10:45:58 2010 -0800

        drm: Set connector DPMS status to ON in drm_crtc_helper_set_config

    And if you'd dig around in the i915 driver code there's even more fun
    around forcing dpms on and losing our heads and temper of the
    resulting inconsistencies. Especially the DP re-training code had tons
    of funny stuff in it.

    Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
    Signed-off-by: Dave Airlie <airlied at redhat.com>

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