Fix checkpatch warning:
WARNING: kfree(NULL) is safe this check is probably not required

Cc: David Airlie <airlied@linux.ie>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>

drm_gem_get_pages() currently allows passing a 'gfp' parameter that is
passed to shmem combined with mapping_gfp_mask(). Given that the default
mapping_gfp_mask() is GFP_HIGHUSER, it is _very_ unlikely that anyone will
ever make use of that parameter. In fact, all drivers currently pass
redundant flags or 0.

This patch removes the 'gfp' parameter. The only reason to keep it is to
remove flags like __GFP_WAIT. But in its current form, it can only be used
to add flags. So to remove __GFP_WAIT, you'd have to drop it from the
mapping_gfp_mask, which again is stupid as this mask is used by shmem-core
for other allocations, too.

If any driver ever requires that parameter, we can introduce a new helper
that takes the raw 'gfp' parameter. The caller'd be responsible to combine
it with mapping_gfp_mask() in a suitable way. The current
drm_gem_get_pages() helper would then simply use mapping_gfp_mask() and
call the new helper. This is what shmem_read_mapping_pages{_gfp,} does
right now.

Moreover, the gfp-zone flag-usage is not obvious: If you pass a modified
zone, shmem core will WARN() or even BUG(). In other words, the following
must be true for 'gfp' passed to shmem_read_mapping_pages_gfp():
    gfp_zone(mapping_gfp_mask(mapping)) == gfp_zone(gfp)
Add a comment to drm_gem_read_pages() explaining that constraint.
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>

OMAP requires bo-pages to be in the DMA32 zone. Explicitly request this by
setting __GFP_DMA32 as mapping-gfp-mask during shmem initialization. This
drops HIGHMEM from the gfp-mask and uses DMA32 instead. shmem-core takes
care to relocate pages during swap-in in case they have been loaded into
the wrong zone.

It is _not_ possible to pass __GFP_DMA32 to shmem_read_mapping_page_gfp()
as the page might have already been swapped-in at that time. The zone-mask
must be set during initialization and be kept constant for now.

Remove the now superfluous TODO in omap_gem.c.
Reviewed-by: NRob Clark <robdclark@gmail.com>
Tested-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>

All drm_fb_helper_restore_fbdev_mode() call sites, save one, do the same
locking.  Simplify this into drm_fb_helper_restore_fbdev_mode_unlocked().
Signed-off-by: NRob Clark <robdclark@gmail.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

For atomic, it will be quite necessary to not need to care so much
about locking order.  And 'state' gives us a convenient place to stash a
ww_ctx for any sort of update that needs to grab multiple crtc locks.

Because we will want to eventually make locking even more fine grained
(giving locks to planes, connectors, etc), split out drm_modeset_lock
and drm_modeset_acquire_ctx to track acquired locks.

Atomic will use this to keep track of which locks have been acquired
in a transaction.

v1: original
v2: remove a few things not needed until atomic, for now
v3: update for v3 of connection_mutex patch..
v4: squash in docbook
v5: doc tweaks/fixes
Signed-off-by: NRob Clark <robdclark@gmail.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

After the split-out of crtc locks from the big mode_config.mutex
there's still two major areas it protects:
- Various connector probe states, like connector->status, EDID
  properties, probed mode lists and similar information.
- The links from connector->encoder and encoder->crtc and other
  modeset-relevant connector state (e.g. properties which control the
  panel fitter).

The later is used by modeset operations. But they don't really care
about the former since it's allowed to e.g. enable a disconnected VGA
output or with a mode not in the probed list.

Thus far this hasn't been a problem, but for the atomic modeset
conversion Rob Clark needs to convert all modeset relevant locks into
w/w locks. This is required because the order of acquisition is
determined by how userspace supplies the atomic modeset data. This has
run into troubles in the detect path since the i915 load detect code
needs _both_ protections offered by the mode_config.mutex: It updates
probe state and it needs to change the modeset configuration to enable
the temporary load detect pipe.

The big deal here is that for the probe/detect users of this lock a
plain mutex fits best, but for atomic modesets we really want a w/w
mutex. To fix this lets split out a new connection_mutex lock for the
modeset relevant parts.

For simplicity I've decided to only add one additional lock for all
connector/encoder links and modeset configuration states. We have
piles of different modeset objects in addition to those (like bridges
or panels), so adding per-object locks would be much more effort.

Also, we're guaranteed (at least for now) to do a full modeset if we
need to acquire this lock. Which means that fine-grained locking is
fairly irrelevant compared to the amount of time the full modeset will
take.

I've done a full audit, and there's just a few things that justify
special focus:
- Locking in drm_sysfs.c is almost completely absent. We should
  sprinkle mode_config.connection_mutex over this file a bit, but
  since it already lacks mode_config.mutex this patch wont make the
  situation any worse. This is material for a follow-up patch.

- omap has a omap_framebuffer_flush function which walks the
  connector->encoder->crtc links and is called from many contexts.
  Some look like they don't acquire mode_config.mutex, so this is
  already racy. Again fixing this is material for a separate patch.

- The radeon hot_plug function to retrain DP links looks at
  connector->dpms. Currently this happens without any locking, so is
  already racy. I think radeon_hotplug_work_func should gain
  mutex_lock/unlock calls for the mode_config.connection_mutex.

- Same applies to i915's intel_dp_hot_plug. But again, this is already
  racy.

- i915 load_detect code needs to acquire this lock. Which means the
  w/w dance due to Rob's work will be nicely contained to _just_ this
  function.

I've added fixme comments everywhere where it looks suspicious but in
the sysfs code. After a quick irc discussion with Dave Airlie it
sounds like the lack of locking in there is due to sysfs cleanup fun
at module unload.

v1: original (only compile tested)

v2: missing mutex_init(), etc (from Rob Clark)

v3: i915 needs more care in the conversion:
- Protect the edp pp logic with the connection_mutex.
- Use connection_mutex in the backlight code due to
  get_pipe_from_connector.
- Use drm_modeset_lock_all in suspend/resume paths.
- Update lock checks in the overlay code.

Cc: Alex Deucher <alexdeucher@gmail.com>
Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NRob Clark <robdclark@gmail.com>

With the recent primary-plane changes for drm, the primary plane's
framebuffer needs to be ref counted the same way as for
non-primary-planes. This was not done by the omapdrm driver, which
caused the ref count to drop to 0 too early, causing problems.

This patch moves the fb unref and ref from omap_plane_update to
omap_plane_mode_set. This way the fb refs are updated for both primary
and non-primary cases, as omap_plane_update calls omap_plane_mode_set.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The vblank_cb callback and the page_flip ioctl can occur together in different
CPU contexts. vblank_cb uses takes tje drm device's event_lock spinlock when
sending the vblank event and updating omap_crtc->event and omap_crtc->od_fb.

Use the same spinlock in page_flip, to make sure the above omap_crtc parameters
are configured sequentially.
Signed-off-by: NArchit Taneja <archit@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

omap_crtc->old_fb is used to check whether the previous page flip has completed
or not. However, it's never initialized to anything, so it's always NULL. This
results in the check to always succeed, and the page_flip to proceed.

Initialize old_fb to the fb that we intend to flip to through page_flip, and
therefore prevent a future page flip to proceed if the last one didn't
complete.
Signed-off-by: NArchit Taneja <archit@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The channel_names list didn't have a string populated for LCD3 manager, this
results in a crash when the display's output is connected to LCD3. Add an entry
for LCD3.
Reported-by: NSomnath Mukherjee <somnath@ti.com>
Signed-off-by: NArchit Taneja <archit@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

A waiter of the type OMAP_GEM_READ should wait for a buffer to be completely
written, and only then proceed with reading it. A similar logic applies for
waiters with OMAP_GEM_WRITE flag.

Currently the function is_waiting() waits on the read_complete/read_target
counts in the sync object.

This should be the other way round, as a reader should wait for users who are
'writing' to this buffer, and vice versa.

Make readers of the buffer(OMAP_GEM_READ) wait on the write counters, and
writers to the buffer(OMAP_GEM_WRITE) wait on the read counters in is_waiting()
Signed-off-by: NArchit Taneja <archit@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

In omap_gem_op_async(), if a waiter is not added to the wait list, it needs to
be free'd in the function itself.

Make sure we free the waiter for this case.
Signed-off-by: NSubhajit Paul <subhajit_paul@ti.com>
Signed-off-by: NArchit Taneja <archit@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

Patch dfe96ddc (omapdrm: simplify locking in
the fb debugfs file) removed taking locks when using omapdrm's debugfs
to dump fb objects.

However, in omap_gem_describe we give a WARN is the lock has not been
taken, so that WARN is now seen every time omapdrm debugfs is used.

So, presuming the removal of locks is ok, we can also remove the WARN.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

All the planes, including primary planes, are now destroyed by the drm
framework. Thus we no longer need the explicit call to plane->destroy
from the crtc's destroy function.

This patch removes the call, thus fixing the crash caused by double
freeing the plane.

remove omap_crtc->plane->funcs->destroy(omap_crtc->plane)
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

Print a warning when the user tries to rotate a non-TILER framebuffer.

Also set the rotation to 0, to avoid constant flood of the warnings in
case of page flipping.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

omap_fbdev_create() takes a reference to the fb's gem object with
omap_gem_get_paddr(). However, it never releases it with
omap_gem_put_paddr().

This patch adds the missing omap_gem_put_paddr() to omap_fbdev_free().
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

Plane rotation with omapdrm is currently broken.
It seems omap_plane_mode_set() expects width and height in screen
coordinates, so pass it like that.
Signed-off-by: NGrazvydas Ignotas <notasas@gmail.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

At the moment the omap_crtc_pre_apply() handles the enabling, disabling
and configuring of encoders and panels separately from the CRTC (i.e.
the overlay manager).

However, this doesn't work correctly. The encoder driver has to be in
control of its video input (i.e. the crtc) for correct operation.

This problem causes bugs with (at least) HDMI: the HDMI encoder supplies
pixel clock for DISPC, and DISPC supplies video stream for HDMI. The
current code first enables the HDMI encoder, and CRTC after that.
However, the encoder expects the video stream to start during the
encoder's enable, and if it doesn't, there will be sync lost errors.

The encoder enables its video source by calling src->enable(), and this
call goes to omapdrm (omap_crtc_enable), but omapdrm doesn't do anything
in that function. Similarly for disable, which goes to
omap_crtc_disable().

This patch moves the code to setup and enable/disable the crtc to
omap_crtc_enable. and omap_crtc_disable().
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>

When an encoder is no longer connected to a crtc, the driver will leave
the encoder enabled.

This patch adds code to track the encoder used for a crtc, and when the
encoder changes, the old one is disabled.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>

At module unload, omap_fbdev_free() gets called which releases the
framebuffers. However, the framebuffers are still used by crtcs, and
will be released only later at vsync. The driver doesn't wait for this,
and goes on to release the rest of the resources, which often
causes a crash.

This patchs adds a omap_crtc_flush() function which waits until the crtc
has finished with its apply queue and page flips.

The function utilizes a simple polling while-loop, as the performance is
not an issue here.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>

At the moment the DMM driver is never unregistered, even if it's
registered in the omapdrm module's init function. This means we'll get
errors when reloading the omapdrm module.

Fix this by unregistering the DMM driver properly, and also change the
module init to fail if DMM driver cannot be registered, simplifying the
unregister path as we don't need to keep the state whether we registered
the DMM driver or not.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>

When unloading omapdrm driver, the omapdrm platform device is
uninitialized last, after the displays have been disconnected omap_crtc
callbacks have been removed. As the omapdrm pdev uninitialization needs
the features uninitialized in earlier steps, a crash is guaranteed.

This patch fixes the uninitialize order so that the omapdrm pdev is
removed first.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>

At the moment it's quite easy to get the following errors when the HDMI
output is enabled or disabled:

[drm:omap_crtc_error_irq] *ERROR* tv: errors: 00008000

The reason for the errors is that the omapdrm driver doesn't properly
handle the sync-lost irqs that happen when enabling the DIGIT crtc,
which is used for HDMI and analog TV. The driver does disable the
sync-lost irq properly, but it fails to wait until the output has been
fully enabled (i.e. the first vsync), so the sync-lost errors are still
seen occasionally.

This patch makes the omapdrm act the same way as the omapfb does:

- When enabling a display, we'll wait for the first vsync.
- When disabling a display, we'll wait for framedone if available, or
  odd and even vsyncs.

These changes make sure the output is fully enabled or disabled at the
end of the function.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Reported-by: NSanjay Singh Rawat <sanjay.rawat@linaro.org>
Reviewed-by: NRob Clark <robdclark@gmail.com>

Now that CRTC's have a primary plane, there's no need to track the
framebuffer in the CRTC.  Replace all references to the CRTC fb with the
primary plane's fb.

This patch was generated by the Coccinelle semantic patching tool using
the following rules:

        @@ struct drm_crtc C; @@
        -   (C).fb
        +   C.primary->fb

        @@ struct drm_crtc *C; @@
        -   (C)->fb
        +   C->primary->fb

v3: Generate patch via coccinelle.  Actual removal of crtc->fb has been
    moved to a subsequent patch.

v2: Fixup several lingering crtc->fb instances that were missed in the
    first patch iteration.  [Rob Clark]
Signed-off-by: NMatt Roper <matthew.d.roper@intel.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>

The connectors list iterator returns the list head when the list is
empty. Fix it by returning NULL in that case.
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>
Signed-off-by: NRob Clark <robdclark@gmail.com>

DRM drivers share a common address_space across all character-devices of a
single DRM device. This allows simple buffer eviction and mapping-control.
However, DRM core currently waits for the first ->open() on any char-dev
to mark the underlying inode as backing inode of the device. This delayed
initialization causes ugly conditions all over the place:
  if (dev->dev_mapping)
    do_sth();

To avoid delayed initialization and to stop reusing the inode of the
char-dev, we allocate an anonymous inode for each DRM device and reset
filp->f_mapping to it on ->open().
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>

omapdss has its own video-timings struct, but we want to move the common
videomode.

The first step is to change the omapdss's pixelclock unit from kHz to
Hz. Also, omapdss uses "pixel_clock" field name, whereas the common
videomode uses "pixelclock" field name. This patch changes the field
name also, as that makes it easy to spot any non-converted pixel_clock
uses.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

This was hidden in a generic void * dev->mm_private. But only ever
used for gem. But thanks to this fake generic pretension no one
noticed that Rob's drm drivers are now all broken.

So just give the offset manager a type pointer and fix up msm, omapdrm
and tilcdc.

v2: Fixup compile fail.

v3: Fixup rebase fail that David spotted.

Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Enable use of DT for DMM/Tiler.

Originally worked on by Andy Gross <andygro@gmail.com>

Cc: Andy Gross <andygro@gmail.com>
Cc: DRI Development <dri-devel@lists.freedesktop.org>
Signed-off-by: NArchit Taneja <archit@ti.com>
[tomi.valkeinen@ti.com: use of_match_ptr()]
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

The current dev_unload order uninits the irqs too early.

In the current sequence, it's possible that a crtc queues work(apply_worker)
to display a buffer, which registers to omap_crtc_apply_irq to notfiy the
completion of the configuration we applied.

Calling drm_vblank_cleanup and omap_drm_irq_uninstall here causes the crtc's
apply handler to never get called, which results in an incorrect state of the
apply_irq.registered parameter.

This condition occurs where there is no mode set via omapdrm, and dev_lastclose
tries to set a default fb mode via drm_fb_helper_restore_fbdev_mode. The apply
work scheduled by restore_fbdev_mode is very close in time to the disabling of
the irq handler, and hence leads to a race condition. We move the irq cleanup
at the end of the unload sequence to prevent this.

Also, the call to flush_workqueue is removed since it's called internally by
destroy_workqueue.
Signed-off-by: NArchit Taneja <archit@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

Currently, an encoder is disabled only when an apply work is queued for the
corresponding crtc. This works fine for the paths where userspace explicitly
disables crtc, this results in disabling the omapdss device in the crtc's
pre_apply function.

However, when the omapdrm module is removed, there is no work queued to ensure
that the encoder is disabled. This can result in an enabled omapdss device when
removing omapdrm. omapdss is left in an inconsistent state, and that prevents us
from using that omapdss device being used again.

Disable enabled encoders in omap_encoder_destroy, we could consider a better
place for doing this later.
Signed-off-by: NArchit Taneja <archit@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

At omapdrm probe, we install manager ops and connect omapdss devices. This
needs to be undone when omapdrm module is removed so that omapdss is in a
clean state. This ensures that we can re-insert omapdrm module, or some other
module which uses omapdss(like omapfb/omap_vout).

Currently, omapdrm's remove neither uninstalls manager ops, or disconnects
omapdss devices. We make sure that this is done in pdev_remove.

omapdrm establishes connections for omap_dss_device devices when probed. It
should also be responsible to disconnect the devices. Keeping the devices
connected can prevent the panel driver modules from unloading, it also causes
issues when we try to remove or re-insert omapdrm module.
Signed-off-by: NArchit Taneja <archit@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

With the omapdss device model changes. omapdrm is required to call dssdriver's
connect() op to register a panel. This is currently done in omap_modeset_init()

A call to connect() can fail if the omapdss panels or the encoders(HDMI/DPI)
they connect to have some resource(like regulators, I2C adapter) missing. If
this happens, the correct approach is to defer omapdrm's probe.

omapdrm currently ignores those panels which return a non zero value when
connected. This could result in omapdrm ignoring all panels on an omap board.

The right approach would be for omapdrm to request for probe deferral when a
panel's connect op returns -EPROBE_DEFER.

In order to do this, we need to call connect() much earlier during omapdrm's
probe to prevent too many things are already done by then. We now connect the
panels during pdev_probe(), before anything else is initialized, so that we
don't need to undo too many things if a defer was requested.

Now when we enter omap_modeset_init(), we have a set of panels that have been
connected. We now proceed with registering only those panels that are already
connected.

A special case has to be considered when no panels are available to connect when
omapdrm probes. In this case too, we defer probe and expect that a panel will be
available to connect the next time.

Checking whether the panel has a driver or whether it has get_timing/read_edid
ops in omap_modeset_init() are redundant with the new display model. These can
be removed since a dssdev device will always have a driver associated with it,
and all dssdev drivers have a get_timings op.

This will mainly fix cases when omapdrm is built-in the kernel, since that's
generally where resources like regulators or I2C are unavailable because of
probe order dependencies.

In particular this fixes boot with omapdrm built-in on an omap4 panda ES board.
The regulators used by HDMI(provided by I2C based TWL regulators) aren't
initialized because I2C isn't initialized, I2C isn't initialized as it's pins
are not configured because pinctrl is yet to probe.
Signed-off-by: NArchit Taneja <archit@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

omapdrm (un)registers irqs inside an irq handler. The problem is that
the (un)register function uses dispc_runtime_get/put() to enable the
clocks, and those functions are not irq safe by default.

This was kind of fixed in 48664b21
(OMAPDSS: DISPC: set irq_safe for runtime PM), which makes dispc's
runtime calls irq-safe.

However, using pm_runtime_irq_safe in dispc makes the parent of dispc,
dss, always enabled, effectively preventing PM for the whole DSS module.

This patch makes omapdrm behave better by adding new irq (un)register
functions that do not use dispc_runtime_get/put, and using those
functions in interrupt context. Thus we can make dispc again
non-irq-safe, allowing proper PM.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Rob Clark <robdclark@gmail.com>

Less yelling ftw!
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

I've killed them a long time ago in drm/i915, let's get rid of this
remnant of shared drm core days for good.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Again omap already sets the driver data pointer to the drm_device.

Also drop the driver unregister call, that should be (and already is)
done in the module unload hook.

Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Not all drivers will need take all the modeset locks for dirtyfb, so
push the locking down to the drivers.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NJakob Bornecrantz <jakob@vmware.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

The correct way for a driver to specify the coherent DMA mask is
not to directly access the field in the struct device, but to use
dma_set_coherent_mask().  Only arch and bus code should access this
member directly.

Convert all direct write accesses to using the correct API.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

For drivers which might want to disable fbdev legacy support.

Select the new option in all drivers for now, so this shouldn't result
in any change. Drivers need some work anyway to make fbdev support
optional (if they have it implemented, that is), so the recommended
way to expose this is by adding per-driver options. At least as long
as most drivers don't support disabling the fbdev support.

v2: Update for new drm drivers msm and rcar-du. Note that Rob's msm
driver can already take advantage of this, which allows us to build
msm without any fbdev depencies in the kernel!

v3: Move the MODULE_* stuff from the fbdev helper file to
drm_crtc_helper.c.

Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Rob Clark <robdclark@gmail.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>
Acked-by: NDave Airlie <airlied@linux.ie>
Reviewed-by: NChon Ming Lee <chon.ming.lee@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>