Backmerge the drm-fixes pull from Linus's tree into drm-next.

This is to fix some conflicts and make future pulls cleaner

With atomic drivers we need to make sure that (at least in general)
property reads hold the right locks. But the legacy dpms property is
special and can be read locklessly. Since userspace loves to just
randomly look at that all the time (like with "status") do that.

To make it clear that we play tricks use the READ_ONCE compiler
barrier (and also for paranoia).

Note that there's not really anything bad going on since even with the
new atomic paths we eventually end up not chasing any pointers (and
hence possibly freed memory and other fun stuff). The locking WARNING
has been added in

commit 88a48e297b3a3bac6022c03babfb038f1a886cea
Author: Rob Clark <robdclark@gmail.com>
Date:   Thu Dec 18 16:01:50 2014 -0500

    drm: add atomic properties

but since drivers are converting not everyone will have seen this from
the start.

Jens reported this and submitted a patch to just grab the
mode_config.connection_mutex, but we can do a bit better.

v2: Remove unused variables I failed to git add for real.

Reference: http://mid.gmane.org/20150928194822.GA3930@kernel.dk
Reported-by: Jens Axboe <axboe@fb.com>
Tested-by: Jens Axboe <axboe@fb.com>
Cc: Rob Clark <robdclark@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

Right now, drm_sysfs_create() returns the newly allocated "struct class"
to the caller (which is drm_core_init()), which then has to set the
global variable 'drm_class'. During cleanup, though, we call
drm_sysfs_destroy() which implicitly uses the global 'drm_class'. This is
confusing, as ownership of the global 'drm_class' is non-obvious.

This patch changes drm_sysfs_create() to drm_sysfs_init() and makes it
initialize the 'drm_class' object directly, rather than returning it.
This way, both drm_sysfs_init() and drm_sysfs_destroy() work in a similar
fashion and manage the global drm class.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Simplify `foo == NULL || IS_ERR(foo)` via IS_ERR_OR_NULL(). This is
pretty commonly used all over the kernel, especially for debugfs/sysfs
cleanup paths.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Pull drm updates from Dave Airlie:
 "This is the main drm pull request for v4.2.

  I've one other new driver from freescale on my radar, it's been posted
  and reviewed, I'd just like to get someone to give it a last look, so
  maybe I'll send it or maybe I'll leave it.

  There is no major nouveau changes in here, Ben was working on
  something big, and we agreed it was a bit late, there wasn't anything
  else he considered urgent to merge.

  There might be another msm pull for some bits that are waiting on
  arm-soc, I'll see how we time it.

  This touches some "of" stuff, acks are in place except for the fixes
  to the build in various configs,t hat I just applied.

  Summary:

  New drivers:
      - virtio-gpu:
                KMS only pieces of driver for virtio-gpu in qemu.
                This is just the first part of this driver, enough to run
                unaccelerated userspace on. As qemu merges more we'll start
                adding the 3D features for the virgl 3d work.
      - amdgpu:
                a new driver from AMD to driver their newer GPUs. (VI+)
                It contains a new cleaner userspace API, and is a clean
                break from radeon moving forward, that AMD are going to
                concentrate on. It also contains a set of register headers
                auto generated from AMD internal database.

  core:
      - atomic modesetting API completed, enabled by default now.
      - Add support for mode_id blob to atomic ioctl to complete interface.
      - bunch of Displayport MST fixes
      - lots of misc fixes.

  panel:
      - new simple panels
      - fix some long-standing build issues with bridge drivers

  radeon:
      - VCE1 support
      - add a GPU reset counter for userspace
      - lots of fixes.

  amdkfd:
      - H/W debugger support module
      - static user-mode queues
      - support killing all the waves when a process terminates
      - use standard DECLARE_BITMAP

  i915:
      - Add Broxton support
      - S3, rotation support for Skylake
      - RPS booting tuning
      - CPT modeset sequence fixes
      - ns2501 dither support
      - enable cmd parser on haswell
      - cdclk handling fixes
      - gen8 dynamic pte allocation
      - lots of atomic conversion work

  exynos:
      - Add atomic modesetting support
      - Add iommu support
      - Consolidate drm driver initialization
      - and MIC, DECON and MIPI-DSI support for exynos5433

  omapdrm:
      - atomic modesetting support (fixes lots of things in rewrite)

  tegra:
      - DP aux transaction fixes
      - iommu support fix

  msm:
      - adreno a306 support
      - various dsi bits
      - various 64-bit fixes
      - NV12MT support

  rcar-du:
      - atomic and misc fixes

  sti:
      - fix HDMI timing complaince

  tilcdc:
      - use drm component API to access tda998x driver
      - fix module unloading

  qxl:
      - stability fixes"

* 'drm-next' of git://people.freedesktop.org/~airlied/linux: (872 commits)
  drm/nouveau: Pause between setting gpu to D3hot and cutting the power
  drm/dp/mst: close deadlock in connector destruction.
  drm: Always enable atomic API
  drm/vgem: Set unique to "vgem"
  of: fix a build error to of_graph_get_endpoint_by_regs function
  drm/dp/mst: take lock around looking up the branch device on hpd irq
  drm/dp/mst: make sure mst_primary mstb is valid in work function
  of: add EXPORT_SYMBOL for of_graph_get_endpoint_by_regs
  ARM: dts: rename the clock of MIPI DSI 'pll_clk' to 'sclk_mipi'
  drm/atomic: Don't set crtc_state->enable manually
  drm/exynos: dsi: do not set TE GPIO direction by input
  drm/exynos: dsi: add support for MIC driver as a bridge
  drm/exynos: dsi: add support for Exynos5433
  drm/exynos: dsi: make use of array for clock access
  drm/exynos: dsi: make use of driver data for static values
  drm/exynos: dsi: add macros for register access
  drm/exynos: dsi: rename pll_clk to sclk_clk
  drm/exynos: mic: add MIC driver
  of: add helper for getting endpoint node of specific identifiers
  drm/exynos: add Exynos5433 decon driver
  ...

Writing to a file is supposed to return the number of bytes written.
Returning zero unfortunately causes bash to constantly spin trying
to write to the sysfs file, to such an extent that even ^c and ^z
have no effect.  The only way out of that is to kill the shell and
log back in.  This isn't nice behaviour.

Fix it by returning the number of characters written to sysfs files.

[airlied: used suggestion from Al Viro]
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>

These attributes should be exposed for the matching connector types
only, so checking is redundant.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

The show methods for the attributes of DVI-I and TV-out types have a
bunch of code to deal with the differences between the two. Just split
the attributes into connector type specific ones. No functional changes.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Split DVI-I and TV-out (which remains a group of types). As an
intermediate step, still share the attributes themselves between the
two. No user visible changes.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

This reduces duplication in the patches to follow. No functional
changes.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>