Make use of ARCH_RENESAS in place of ARCH_SHMOBILE.

This is part of an ongoing process to migrate from ARCH_SHMOBILE to
ARCH_RENESAS the motivation for which being that RENESAS seems to be a more
appropriate name than SHMOBILE for the majority of Renesas ARM based SoCs.
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

The VSP1 compositor code in DRM links against the respective V4L
driver, but the dependency is not expressed correctly in Kconfig,
which leads to a build error when the DRM driver is built-in
and the V4L driver is a module:

drivers/gpu/built-in.o: In function `rcar_du_vsp_plane_atomic_update':
rcar-du/rcar_du_vsp.c:183: undefined reference to `vsp1_du_atomic_update'

This patch avoids the problem by ensuring that the DRM VSP code can
only be enabled if the V4L driver is linked into the kernel, or
both are loadable modules.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Fixes: 6d62ef3a ("drm: rcar-du: Expose the VSP1 compositor through KMS planes")
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

Since ref counting is in the object now we can just call the
normal interfaces.
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

This reduces the fb_lock to just protecting the num_fb/fb_list.

"Previously fb refcounting, and especially the weak reference
(kref_get_unless_zero) used in fb lookups have been protected by fb_lock.
But with the refactoring to share refcounting in the drm_mode_object base
class that switched to being protected by idr_mutex, which means fb_lock
critical sections can be reduced."
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

When we lookup an ref counted object we now take a proper reference
using kref_get_unless_zero.

Framebuffer lookup no longer needs do this itself.

Convert rmfb to using framebuffer lookup and deal with the fact
it now gets an extra reference that we have to cleanup. This should
mean we can avoid holding fb_lock across rmfb. (if I'm wrong let me
know).

We also now only hold the fbs_lock around the list manipulation.

"Previously fb refcounting, and especially the weak reference
(kref_get_unless_zero) used in fb lookups have been protected by fb_lock.
But with the refactoring to share refcounting in the drm_mode_object base
class that switched to being protected by idr_mutex, which means fb_lock
critical sections can be reduced."
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

No need to hold the lock while assigning the variable.

Daniel wrote:
"Not sure why exactly I put that under the lock, but the only thing that
can race here is rmfb while addfb2 is still doing it's thing, with a
correctly guess (easy to do since they're fully deterministic) fb_id."
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

We don't need to hold the fb lock around the initialisation,
only around the list manipulaton.

So do the lock hold only around the register for now.

From Daniel:
Previously fb refcounting, and especially the weak reference
(kref_get_unless_zero) used in fb lookups have been protected by fb_lock.
But with the refactoring to share refcounting in the drm_mode_object base
class that switched to being protected by idr_mutex, which means fb_lock
critical sections can be reduced.
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

No point have this code dupliated at this point, use the
_object_find code instead now.
Signed-off-by: NDave Airlie <airlied@redhat.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is the initial code to add references to some mode objects.
In the future we need to start reference counting connectors so
firstly I want to reorganise the code so the framebuffer ref counting
uses the same paths.

This patch shouldn't change any functionality, just moves the kref.

[airlied: move kerneldoc as well]
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Avoids drivers knowing where the kref is stored.

[airlied: add kerneldoc]
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Just use the generic function.

The main side effect of this is that the fb->base.id
is now protected by the idr mutex as well.
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

A later patch will use it in framebuffer_init, and I want
to keep the diff cleaner.
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

This changes the code to handle being called multiple times without
side effects. The new names seems more suitable for what it does.
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

This PR contains several improvement and cleanup patches for the
atmel-hlcdc driver to be applied on drm-next (targeting 4.7).

* 'drm-atmel-hlcdc-devel' of https://github.com/bbrezillon/linux-at91:
  drm: atmel-hlcdc: route DMA accesses through AHB interfaces
  drm: atmel-hlcdc: check display mode validity in crtc->mode_fixup()
  drm: atmel-hlcdc: rework the output code to support drm bridges
  drm: atmel-hlcdc: move output mode selection in CRTC implementation
  drm: atmel-hlcdc: support extended timing ranges on sama5d4 and sama5d2
  drm: atmel-hlcdc: remove leftovers from atomic mode setting migration
  drm: atmel-hlcdc: fix connector and encoder types
  drm: atmel-hlcdc: support asynchronous atomic commit operations
  drm: atmel-hlcdc: add a ->cleanup_fb() operation

- make modeset hw state checker atomic aware (Maarten)
- close races in gpu stuck detection/seqno reading (Chris)
- tons&tons of small improvements from Chris Wilson all over the gem code
- more dsi/bxt work from Ramalingam&Jani
- macro polish from Joonas
- guc fw loading fixes (Arun&Dave)
- vmap notifier (acked by Andrew) + i915 support by Chris Wilson
- create bottom half for execlist irq processing (Chris Wilson)
- vlv/chv pll cleanup (Ville)
- rework DP detection, especially sink detection (Shubhangi Shrivastava)
- make color manager support fully atomic (Maarten)
- avoid livelock on chv in execlist irq handler (Chris)

* tag 'drm-intel-next-2016-04-11' of git://anongit.freedesktop.org/drm-intel: (82 commits)
  drm/i915: Update DRIVER_DATE to 20160411
  drm/i915: Avoid allocating a vmap arena for a single page
  drm,i915: Introduce drm_malloc_gfp()
  drm/i915/shrinker: Restrict vmap purge to objects with vmaps
  drm/i915: Refactor duplicate object vmap functions
  drm/i915: Consolidate common error handling in intel_pin_and_map_ringbuffer_obj
  drm/i915/dmabuf: Tighten struct_mutex for unmap_dma_buf
  drm/i915: implement WaClearTdlStateAckDirtyBits
  drm/i915/bxt: Reversed polarity of PORT_PLL_REF_SEL bit
  drm/i915: Rename hw state checker to hw state verifier.
  drm/i915: Move modeset state verifier calls.
  drm/i915: Make modeset state verifier take crtc as argument.
  drm/i915: Replace manual barrier() with READ_ONCE() in HWS accessor
  drm/i915: Use simplest form for flushing the single cacheline in the HWS
  drm/i915: Harden detection of missed interrupts
  drm/i915: Separate out the seqno-barrier from engine->get_seqno
  drm/i915: Remove forcewake dance from seqno/irq barrier on legacy gen6+
  drm/i915: Fixup the free space logic in ring_prepare
  drm/i915: Simplify check for idleness in hangcheck
  drm/i915: Apply a mb between emitting the request and hangcheck
  ...

Backmerge 4.6-rc3 for i915.

Linux 4.6-rc3

misc pull req all over. Biggest thing is the
drm_connector_(un)register_all cleanup from Alexey for drivers without the
load/unload midlayer hooks. I.e. all the new ones, and a bunch of the
pending new atomic drivers depend upon this. Or at least I asked them to
rebase ;-)

* tag 'topic/drm-misc-2016-04-21' of git://anongit.freedesktop.org/drm-intel:
  drm: Make drm.debug parameter description more helpful
  drm: Remove warning from drm_connector_unregister_all()
  drm: probe_helper: Hide ugly ifdef
  drm: rcar-du: Use generic drm_connector_register_all() helper
  drm: atmel_hldc: Use generic drm_connector_register_all() helper
  drm: Introduce drm_connector_register_all() helper
  drm: fix lut value extraction function
  drm/atomic-helper: Print an error if vblank wait times out
  drm/dp/mst: Restore primary hub guid on resume
  drm: Release driver references to handle before making it available again
  drm/i915/dp/mst: Add source port info to debugfs output
  drm/dp/mst: Enhance DP MST debugfs output
  drm/edid: Add drm_edid_get_monitor_name()
  include/drm: Reword debug categories comment.
  drm/crtc_helper: Reset empty plane state in drm_helper_crtc_mode_set_base()
  drm/virtio: Drop dummy gamma table support
  drm/bochs: Drop fake gamma support
  drm/core: Fix ordering in drm_mode_config_cleanup.

struct_mutex cleanups and error paths fixes. Unfortunately I didn't manage
to get acks from everyone, but this stuff has been hanging out for months
now and imo simple enough to just land the remaining few patches. But
separate pull request so that you can take a look yourself.

* tag 'topic/struct_mutex-2016-04-21' of git://anongit.freedesktop.org/drm-intel:
  drm/vma_manage: Drop has_offset
  drm/vgem: Drop dev->struct_mutex
  drm/vgem: Move get_pages to gem_create
  drm/vgem: Simplify dumb_map
  drm/exynos: drop struct_mutex from fbdev setup
  drm/exynos: drop struct_mutex from exynos_drm_gem_get_ioctl
  drm/exynos: drop struct_mutex from exynos_gem_map_sgt_with_dma
  drm/exynos: Drop dev->struct_mutex from mmap offset function
  drm/nouveau: Drop dev->struct_mutex from fbdev init
  drm/qxl: Use unlocked gem unreferencing
  drm/omapdrm: Use unlocked gem unreferencing
  drm/nouveau: Use unlocked gem unreferencing

Let's be user-friendly and print an actually helpful parameter
description.

This makes modinfo output the debug parameter like this:

parm:           debug:Enable debug output, where each bit enables a debug category.
		Bit 0 (0x01) will enable CORE messages (drm core code)
		Bit 1 (0x02) will enable DRIVER messages (drm controller code)
		Bit 2 (0x04) will enable KMS messages (modesetting code)
		Bit 3 (0x08) will enable PRIME messages (prime code)
		Bit 4 (0x10) will enable ATOMIC messages (atomic code)
		Bit 5 (0x20) will enable VBL messages (vblank code) (int)

Changes from v1:

  * Fixed s/PRMIE/PRIME typo.
  * Add ATOMIC and VBL debug parameter documentation.
  * Prefix the continuation lines with two tabs and
    removed the last new line.
  * Remove spurious whitespace.
Signed-off-by: NEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461170703-11216-1-git-send-email-ezequiel@vanguardiasur.com.ar

Commit 6c87e5c3 ("drm: Rename drm_connector_unplug_all() to
drm_connector_unregister_all()") replaced a manual connectors list walk
in drm_connector_unregister_all() with drm_for_each_connector(). The
list was walked without the mode config mutex locked as that ends up in
a clash with sysfs, but drm_connector_unregister_all() warns when the
mutex isn't locked.

The problem is known and doesn't require a large warning every time
drm_connector_unregister_all() is called. Fix it by reverting to manual
list walk.

Fixes: 6c87e5c3 ("drm: Rename drm_connector_unplug_all() to drm_connector_unregister_all()")
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461190874-32674-1-git-send-email-laurent.pinchart+renesas@ideasonboard.com

Push the ifdef to the drm_edid.h and create a stub, for the
DRM_LOAD_EDID_FIRMWARE=n case. This removes some clutter in
the code, making it more readable.
Signed-off-by: NEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461087638-16959-1-git-send-email-ezequiel@vanguardiasur.com.ar

Now that a generic drm_connector_register_all() helper exists we may safely
substitute it for the driver-specific implementation of connectors plugging
in sysfs.
Signed-off-by: NAlexey Brodkin <abrodkin@synopsys.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: linux-renesas-soc@vger.kernel.org
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461068693-11260-4-git-send-email-abrodkin@synopsys.com

This driver used to have its own implementation of connector_register_all()
which actually was taken as a prototype of drm_connector_register_all().

Now when drm_connector_register_all() exists reusing it here.
Signed-off-by: NAlexey Brodkin <abrodkin@synopsys.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461068693-11260-3-git-send-email-abrodkin@synopsys.com

As a pair to already existing drm_connector_unregister_all() we're adding
generic implementation of what is already done in some drivers.

Once this helper is implemented we'll be ready to switch existing
driver-specific implementations with the generic one.
Signed-off-by: NAlexey Brodkin <abrodkin@synopsys.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461068693-11260-2-git-send-email-abrodkin@synopsys.com

It's racy, creating mmap offsets is a slowpath, so better to remove it
to avoid drivers doing broken things.

The only user is i915, and it's ok there because everything (well
almost) is protected by dev->struct_mutex in i915-gem.

While at it add a note in the create_mmap_offset kerneldoc that
drivers must release it again. And then I also noticed that
drm_gem_object_release entirely lacks kerneldoc.

Cc: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-14-git-send-email-daniel.vetter@ffwll.ch

With the previous two changes it doesn't protect anything any more.

v2: Use _unlocked unreference variant.

v3: Appease gcc noise.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-13-git-send-email-daniel.vetter@ffwll.ch

vgem doesn't have a shrinker or anything like that and drops backing
storage only at object_free time. There's no use in trying to be
clever and allocating backing storage delayed, it only causes trouble
by requiring locking.

Instead grab pages when we allocate the object right away.

v2: Fix compiling.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-12-git-send-email-daniel.vetter@ffwll.ch

The offset manager already checks for existing offsets internally,
while holding suitable locks. We can drop this check.

v2: Fix title (Emil).
Reviewed-by: NEmil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-11-git-send-email-daniel.vetter@ffwll.ch

Doesn't protect anything at all, and probably just here because a long
time ago dev->struct_mutex was required to allocate gem objects.

With this patch exynos is completely struct_mutex free!

Cc: Inki Dae <inki.dae@samsung.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-10-git-send-email-daniel.vetter@ffwll.ch

The only things this protects is reading ->flags and ->size, both of
which are invariant over the lifetime of an exynos gem bo. So no
locking needed at all (besides that, nothing protects the writers
anyway).

Aside: exynos_gem_obj->size is redundant with
exynos_gem_obj->base.size and probably should be removed.

v2: Use _unlocked unreference (Daniel Stone).

Cc: Daniel Stone <daniel@fooishbar.org>
Cc: Inki Dae <inki.dae@samsung.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-9-git-send-email-daniel.vetter@ffwll.ch

The sg table isn't refcounted, there's no corresponding locking for
unmapping and drm_map_sg is ok with being called concurrently.

So drop the locking since it doesn't protect anything.

Cc: Inki Dae <inki.dae@samsung.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-8-git-send-email-daniel.vetter@ffwll.ch

Simply forgotten about this when I was doing my general cleansing of
simple gem mmap offset functions. There's nothing but core functions
called here, and they all have their own protection already.

Aside: DRM_ERROR for userspace controlled input isn't great, but
that's for another patch.

v2: Use _unlocked unreference (Daniel Stone).

Cc: Daniel Stone <daniel@fooishbar.org>
Cc: Inki Dae <inki.dae@samsung.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-7-git-send-email-daniel.vetter@ffwll.ch

Doesn't protect anything at all.

With this patch nouveau is completely dev->struct_mutex free!

Cc: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-6-git-send-email-daniel.vetter@ffwll.ch

For drm_gem_object_unreference callers are required to hold
dev->struct_mutex, which these paths don't. Enforcing this requirement
has become a bit more strict with

commit ef4c6270
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Oct 15 09:36:25 2015 +0200

    drm/gem: Check locking in drm_gem_object_unreference

Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-4-git-send-email-daniel.vetter@ffwll.ch
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-5-git-send-email-daniel.vetter@ffwll.ch

For drm_gem_object_unreference callers are required to hold
dev->struct_mutex, which these paths don't. Enforcing this requirement
has become a bit more strict with

commit ef4c6270
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Oct 15 09:36:25 2015 +0200

    drm/gem: Check locking in drm_gem_object_unreference

Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-3-git-send-email-daniel.vetter@ffwll.ch

For drm_gem_object_unreference callers are required to hold
dev->struct_mutex, which these paths don't. Enforcing this requirement
has become a bit more strict with

commit ef4c6270
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Oct 15 09:36:25 2015 +0200

    drm/gem: Check locking in drm_gem_object_unreference

Cc: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459330852-27668-2-git-send-email-daniel.vetter@ffwll.ch

When extracting the value at full precision (16 bits), no need to
round the value.

This was spotted by Jani when running sparse. Unfortunately this fix
doesn't get rid of the warning.
Signed-off-by: NLionel Landwerlin <lionel.g.landwerlin@intel.com>
Reported-by: NJani Nikula <jani.nikula@intel.com>
Cc: Daniel Stone <daniels@collabora.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: dri-devel@lists.freedesktop.org
Fixes: 5488dc16 ("drm: introduce pipe color correction properties")
Reviewed-by: NEmil Velikov <emil.velikov@collabora.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1458655833-19547-1-git-send-email-lionel.g.landwerlin@intel.com

Vblank waits timing out is no a normal thing to happen, so let's inform
people when it happens.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1460978973-24945-2-git-send-email-ville.syrjala@linux.intel.com

Some hubs are forgetful, and end up forgetting whatever GUID we set
previously after we do a suspend/resume cycle. This can lead to
hotplugging breaking (along with probably other things) since the hub
will start sending connection notifications with the wrong GUID. As
such, we need to check on resume whether or not the GUID the hub is
giving us is valid.
Signed-off-by: NLyude <cpaul@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>
Reviewed-by: NHarry Wentland <harry.wentland@amd.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1460580618-7421-1-git-send-email-cpaul@redhat.com

When userspace closes a handle, we remove it from the file->object_idr
and then tell the driver to drop its references to that file/handle.
However, as the file/handle is already available again for reuse, it may
be reallocated back to userspace and active on a new object before the
driver has had a chance to drop the old file/handle references.

Whilst calling back into the driver, we have to drop the
file->table_lock spinlock and so to prevent reusing the closed handle we
mark that handle as stale in the idr, perform the callback and then
remove the handle. We set the stale handle to point to the NULL object,
then any idr_find() whilst the driver is removing the handle will return
NULL, just as if the handle is already removed from idr.

Note: This will be used to have a direct handle -> vma lookup table,
instead of first a handle -> obj lookup, and then an (obj, vm) -> vma
lookup.

v2: Use NULL rather than an ERR_PTR to avoid having to adjust callers.
idr_alloc() tracks existing handles using an internal bitmap, so we are
free to use the NULL object as our stale identifier.
v3: Needed to update the return value check after changing from using
the stale error pointer to NULL.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: dri-devel@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Thierry Reding <treding@nvidia.com>
[danvet: Add note about the use-case.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1460721308-32405-1-git-send-email-chris@chris-wilson.co.uk