My minnow was broken by: drm/i915: Consolidate forcewake code

[Olof Johansson]

Hi Daniel, Mika,

For the first time in a few days, -next was bootable last night. I
noticed that my Minnowboard Max didn't actually boot though, it got
stuck shortly after or during DRM probing:

http://arm-soc.lixom.net/bootlogs/next/next-20150123/minnowmax-x86-minnowmax_defconfig.html

I bisected it down to the below patch that I failed to find posted
(with that subject) anywhere on a public list that I am subscribed to.

The patch isn't revertable without considerable effort so I can't
double check that it's just this one change, but the commit before
that in the branch boots, this one does not.


commit fc72355f5c04c40f2916a07e9f8d4b357e2e0a93
Author:     Mika Kuoppala <mika.kuoppala at linux.intel.com>
AuthorDate: Mon Jan 19 16:20:43 2015 +0200
Commit:     Daniel Vetter <daniel.vetter at ffwll.ch>
CommitDate: Tue Jan 20 12:36:57 2015 +0100

    drm/i915: Consolidate forcewake code

    As we now have forcewake domains, take advantage of it
    by putting the differences in gen fw handling in data rather
    than in code.

    In past we have opencoded this quite extensively as the fw handling
    is in the fast path. There has also been a lot of cargo-culted
    copy'n'pasting from older gens to newer ones.

    Now when the releasing of the forcewake is done by deferred timer,
    it gives chance to consolidate more. Due to the frequency of actual hw
    access being significantly less.

    Take advantage of this and generalize the fw handling code
    as much as possible. But we still aim to keep the forcewake sequence
    particularities for each gen intact. So the access pattern
    to fw engines should remain the same.

    v2: - s/old_ack/clear_ack (Chris)
        - s/post_read/posting_read (Chris)
        - less polite commit msg (Chris)

    v3: - rebase
        - check and clear wake_count in init

    v4: - fix posting reads for gen8 (PRTS)

    Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
    Reviewed-by: Deepak S <deepak.s at linux.intel.com> (v2)
    Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>