drm/i915: hold forcewake around ring hw init
authorDaniel Vetter <daniel.vetter@ffwll.ch>
Mon, 4 Jun 2012 09:18:15 +0000 (11:18 +0200)
committerDaniel Vetter <daniel.vetter@ffwll.ch>
Mon, 4 Jun 2012 18:25:29 +0000 (20:25 +0200)
commitb7884eb45ec98c0d34c7f49005ae9d4b4b4e38f6
treef7e2366bbf08fd9af1cb6fc48d4cd6e5ba2b8d77
parent3eef8918ff440837f6af791942d8dd07e1a268ee
drm/i915: hold forcewake around ring hw init

Empirical evidence suggests that we need to: On at least one ivb
machine when running the hangman i-g-t test, the rings don't properly
initialize properly - the RING_START registers seems to be stuck at
all zeros.

Holding forcewake around this register init sequences makes chip reset
reliable again. Note that this is not the first such issue:

commit f01db988ef6f6c70a6cc36ee71e4a98a68901229
Author: Sean Paul <seanpaul@chromium.org>
Date:   Fri Mar 16 12:43:22 2012 -0400

    drm/i915: Add wait_for in init_ring_common

added delay loops to make RING_START and RING_CTL initialization
reliable on the blt ring at boot-up. So I guess it won't hurt if we do
this unconditionally for all force_wake needing gpus.

To avoid copy&pasting of the HAS_FORCE_WAKE check I've added a new
intel_info bit for that.

v2: Fixup missing commas in static struct and properly handling the
error case in init_ring_common, both noticed by Jani Nikula.

Cc: stable@vger.kernel.org
Reported-and-tested-by: Yang Guang <guang.a.yang@intel.com>
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=50522
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
drivers/gpu/drm/i915/i915_drv.c
drivers/gpu/drm/i915/i915_drv.h
drivers/gpu/drm/i915/intel_ringbuffer.c