drm/i915: Treat crtc->mode.clock == 0 as disabled
authorChris Wilson <chris@chris-wilson.co.uk>
Mon, 7 Jan 2013 10:11:40 +0000 (10:11 +0000)
committerDaniel Vetter <daniel.vetter@ffwll.ch>
Mon, 7 Jan 2013 16:40:19 +0000 (17:40 +0100)
commit3490ea5de6ac4af309c3df8a26a5cca61306334c
tree6adbd7881412b084fb3ba05080231122fb63e4f5
parent48e858340dae43189a4e55647f6eac736766f828
drm/i915: Treat crtc->mode.clock == 0 as disabled

Prevent a divide-by-zero by consistently treating an 'active' CRTC
without a mode set as actually disabled.

This looks to have been first introduced with

commit 24929352481f085c5f85d4d4cbc919ddf106d381
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Mon Jul 2 20:28:59 2012 +0200

    drm/i915: read out the modeset hw state at load and resume time

but then combined with

commit b0a2658acb5bf9ca86b4aab011b7106de3af0add
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue Dec 18 09:37:54 2012 +0100

    drm/i915: don't disable disconnected outputs

it finally started oopsing.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reported-and-tested-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
drivers/gpu/drm/i915/intel_pm.c