When tegra-drm.ko is built as a module, these MODULE_DEVICE_TABLEs allow
the module to be auto-loaded since the module will match the devices
instantiated from device tree.

(Notes for stable: in 3.14+, just git rm any conflicting file, since they
are added in later kernels. For 3.13 and below, manual merging will be
needed)

Cc: <stable@vger.kernel.org>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Since the device will no longer be used, may as well keep it in reset to
potentially save some power and make sure it is in a clean state the
next time it's probed.
Signed-off-by: Thierry Reding <treding@nvidia.com>

Tegra20 and Tegra30 both required the buffer line stride to be aligned
on 8 byte boundaries. Tegra114 and Tegra124 increased the alignment to
64 bytes. Introduce a parameter to specify the alignment requirements
for each display controller and round up the pitch of newly allocated
framebuffers appropriately.
Originally-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Program the sync signal polarities according to the display mode.
Signed-off-by: Thierry Reding <treding@nvidia.com>

This change uses the value of bits-per-color from panel to remove one
more hardcoded value.
Signed-off-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Job submission currently relies on the fact that struct drm_tegra_reloc
and struct host1x_reloc are the same size and uses a simple call to the
copy_from_user() function to copy them to kernel space. This causes the
handle to be stored in the buffer object field, which then needs a cast
to a 32 bit integer to resolve it to a proper buffer object pointer and
store it back in the buffer object field.

On 64-bit architectures that will no longer work, since pointers are 64
bits wide whereas handles will remain 32 bits. This causes the sizes of
both structures to because different and copying will no longer work.

Fix this by adding a new function, host1x_reloc_get_user(), that copies
the structures field by field.

While at it, use substructures for the command and target buffers in
struct host1x_reloc for better readability. Also use unsized types to
make it more obvious that this isn't part of userspace ABI.
Signed-off-by: Thierry Reding <treding@nvidia.com>

This matches what other drivers do for equivalent IOCTLs.
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Tested-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

The DRM_TEGRA_GEM_SET_FLAGS IOCTL can be used to set the flags of a
buffer object after it has been allocated or imported. Flags associated
with a buffer object can be queried using the DRM_TEGRA_GEM_GET_FLAGS
IOCTL.
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Tested-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Currently the tiling parameters of buffer objects can only be set at
allocation time, and only a single tiled mode is supported. This new
DRM_TEGRA_GEM_SET_TILING IOCTL allows more modes to be set and also
allows the tiling mode to be changed after the allocation. This will
enable the Tegra DRM driver to import buffers from a GPU and directly
scan them out by configuring the display controller appropriately.

To complement this, the DRM_TEGRA_GEM_GET_TILING IOCTL can query the
current tiling mode of a buffer object. This is necessary when importing
buffers via handle (as is done in Mesa for example) so that userspace
can determine the proper parameters for the 2D or 3D engines.
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Tested-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Tegra124 supports a block-linear mode in addition to the regular pitch
linear and tiled modes. Add support for these by moving the internal
representation into a structure rather than a simple flag.
Tested-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Handle the MIPI_DSI_CLOCK_NONCONTINUOUS flag and only set TX-only
clock behavior when this flag is present to allow panels requiring
continuous clock mode to operate with this driver.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

We should unlock before returning the error code.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

* drm/dsi/for-next:
  drm/dsi: Flag for non-continuous clock behavior

As per section 5.6.1 of the DSI specification, all DSI transmitters must
support continuous clock behavior on the clock lane, while non-continuous
mode support is only optional. Add a flag that allows devices to indicate
that they support non-continuous clock mode so host drivers can adapt
their behavior accordingly.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

A race condition currently exists on Tegra, where it can happen that a
monitor attached via HDMI isn't detected during the initial FB helper
setup, but the hotplug event happens too early to be processed by the
poll helpers because they haven't been initialized yet. This happens
because on some boards the HDMI driver can control the regulator that
supplies the +5V pin on the HDMI connector. Therefore depending on the
timing between the initialization of the HDMI driver and the rest of
DRM, it's possible that the monitor returns the hotplug signal right
within the window where we would miss it.

Unfortunately, drm_kms_helper_poll_init() will wreak havoc when called
before at least some parts of the FB helpers have been set up.

This commit fixes this by splitting out the minimum of initialization
required to make drm_kms_helper_poll_init() work into a separate
function that can be called early. It is then safe to move all of the
poll helper initialization to an earlier point in time (before the
HDMI output driver has a chance to enable the +5V supply). That way if
the hotplug signal is returned before the initial FB helper setup, the
monitor will be forcefully detected at that point, and if the hotplug
signal is returned after that it will be properly handled by the poll
helpers.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

To implement hotplug detection in a race-free manner, drivers must call
drm_kms_helper_poll_init() before hotplug events can be triggered. Such
events can be triggered right after any of the encoders or connectors
are initialized. At the same time, if the drm_fb_helper_hotplug_event()
helper is used by a driver, then the poll helper requires some parts of
the FB helper to be initialized to prevent a crash.

At the same time, drm_fb_helper_init() requires information that is not
necessarily available at such an early stage (number of CRTCs and
connectors), so it cannot be used yet.

Add a new helper, drm_fb_helper_prepare(), that initializes the bare
minimum needed to allow drm_kms_helper_poll_init() to execute and any
subsequent hotplug events to be processed properly.
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

There's no need for this to be modifiable. Make it const so that it can
be put into the .rodata section.
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>

Some drivers need to be able to have a perfect race-free fbcon setup.
Current drivers only enable hotplug processing after the call to
drm_fb_helper_initial_config which leaves a tiny but important race.

This race is especially noticable on embedded platforms where the
driver itself enables the voltage for the hdmi output, since only then
will monitors (after a bit of delay, as usual) respond by asserting
the hpd pin.

Most of the infrastructure is already there with the split-out
drm_fb_helper_init. And drm_fb_helper_initial_config already has all
the required locking to handle concurrent hpd events since

commit 53f1904b
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Mar 20 14:26:35 2014 +0100

    drm/fb-helper: improve drm_fb_helper_initial_config locking

The only missing bit is making drm_fb_helper_hotplug_event save
against concurrent calls of drm_fb_helper_initial_config. The only
unprotected bit is the check for fb_helper->fb.

With that drivers can first initialize the fb helper, then enabel
hotplug processing and then set up the initial config all in a
completely race-free manner. Update kerneldoc and convert i915 as a
proof of concept.

Feature requested by Thierry since his tegra driver atm reliably boots
slowly enough to misses the hotplug event for an external hdmi screen,
but also reliably boots to quickly for the hpd pin to be asserted when
the fb helper calls into the hdmi ->detect function.

Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

Fix a sparse warning: ttm_bo_reserve()'s last argument is a
pointer to a struct, so use NULL as nullpointer.
Signed-off-by: Martin Kepplinger <martink@posteo.de>
Reviewed-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

Use module_init instead of late_initcall, as is the norm for modular
drivers.

module_init was used until 6e8de0bd
("drm/tilcdc: add encoder slave (v2)") changed it to a late_initcall,
but it does not explain why. Tests show it's working properly with
module_init.
Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Tested-by: Darren Etheridge <detheridge@ti.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

The TI tilcdc driver is designed with a notion of submodules. Currently,
at unload time, these submodules are iterated and destroyed.

Now that the tilcdc remove order is fixed, this can be handled perfectly
by the kernel using the device infrastructure, since each submodule
is a kernel driver itself, and they are only destroy()'ed at unload
time. Therefore we move the destroy() functionality to each submodule's
remove().

Also, remove some checks in the unloading process since the new code
guarantees the resources are allocated and need a release.
Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Tested-by: Darren Etheridge <detheridge@ti.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

display_timings_release calls kfree on the display_timings object passed
to it. Calling kfree after it is wrong. SLUB debug showed the following
warning:

    =============================================================================
    BUG kmalloc-64 (Tainted: G        W    ): Object already free
    -----------------------------------------------------------------------------

    Disabling lock debugging due to kernel taint
    INFO: Allocated in of_get_display_timings+0x2c/0x214 age=601 cpu=0
    pid=884
     __slab_alloc.constprop.79+0x2e0/0x33c
     kmem_cache_alloc+0xac/0xdc
     of_get_display_timings+0x2c/0x214
     panel_probe+0x7c/0x314 [tilcdc]
     platform_drv_probe+0x18/0x48
     [..snip..]
    INFO: Freed in panel_destroy+0x18/0x3c [tilcdc] age=0 cpu=0 pid=907
     __slab_free+0x34/0x330
     panel_destroy+0x18/0x3c [tilcdc]
     tilcdc_unload+0xd0/0x118 [tilcdc]
     drm_dev_unregister+0x24/0x98
     [..snip..]
Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Tested-by: Darren Etheridge <detheridge@ti.com>
Cc: <stable@vger.kernel.org> #v3.9+
Signed-off-by: Dave Airlie <airlied@redhat.com>

Unregister resources in the correct order on tilcdc_drm_fini, which is
the reverse order they were registered during tilcdc_drm_init.

This also means unregistering the driver before releasing its resources.
Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Tested-by: Darren Etheridge <detheridge@ti.com>
Cc: <stable@vger.kernel.org> #v3.9+
Signed-off-by: Dave Airlie <airlied@redhat.com>

The driver did not unregister the allocated framebuffer, which caused
memory leaks (and memory manager WARNs) when unloading. Also, the
framebuffer device under /dev still existed after unloading.

Add a call to drm_fbdev_cma_fini when unloading the module to prevent
both issues.
Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Tested-by: Darren Etheridge <detheridge@ti.com>
Cc: <stable@vger.kernel.org> #v3.9+
Signed-off-by: Dave Airlie <airlied@redhat.com>

Add a drm_sysfs_connector_remove call when we destroy the panel to make
sure the connector node in sysfs gets deleted.

This is required for proper unload and re-load of this driver, otherwise
we will get a warning about a duplicate filename in sysfs.
Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Tested-by: Darren Etheridge <detheridge@ti.com>
Cc: <stable@vger.kernel.org> #v3.9+
Signed-off-by: Dave Airlie <airlied@redhat.com>

Add a drm_sysfs_connector_remove call when we destroy the panel to make
sure the connector node in sysfs gets deleted.

This is required for proper unload and re-load of this driver as a
module. Without this, we would get a warning at re-load time like so:

   tda998x 0-0070: found TDA19988
   ------------[ cut here ]------------
   WARNING: CPU: 0 PID: 825 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x54/0x74()
   sysfs: cannot create duplicate filename '/class/drm/card0-HDMI-A-1'
   Modules linked in: [..]
   CPU: 0 PID: 825 Comm: modprobe Not tainted 3.15.0-rc4-00027-g9dcdef4 #82
   [<c0013bb8>] (unwind_backtrace) from [<c0011824>] (show_stack+0x10/0x14)
   [<c0011824>] (show_stack) from [<c0034e8c>] (warn_slowpath_common+0x68/0x88)
   [<c0034e8c>] (warn_slowpath_common) from [<c0034edc>] (warn_slowpath_fmt+0x30/0x40)
   [<c0034edc>] (warn_slowpath_fmt) from [<c01243f4>] (sysfs_warn_dup+0x54/0x74)
   [<c01243f4>] (sysfs_warn_dup) from [<c0124708>] (sysfs_do_create_link_sd.isra.2+0xb0/0xb8)
   [<c0124708>] (sysfs_do_create_link_sd.isra.2) from [<c02ae37c>] (device_add+0x338/0x520)
   [<c02ae37c>] (device_add) from [<c02ae6e8>] (device_create_groups_vargs+0xa0/0xc4)
   [<c02ae6e8>] (device_create_groups_vargs) from [<c02ae758>] (device_create+0x24/0x2c)
   [<c02ae758>] (device_create) from [<c029b4ec>] (drm_sysfs_connector_add+0x64/0x204)
   [<c029b4ec>] (drm_sysfs_connector_add) from [<bf0b1b40>] (slave_modeset_init+0x120/0x1bc [tilcdc])
   [<bf0b1b40>] (slave_modeset_init [tilcdc]) from [<bf0b2be8>] (tilcdc_load+0x214/0x4c0 [tilcdc])
   [<bf0b2be8>] (tilcdc_load [tilcdc]) from [<c029955c>] (drm_dev_register+0xa4/0x104)
      [..snip..]
   ---[ end trace 4df8d614936ebdee ]---
   [drm:drm_sysfs_connector_add] *ERROR* failed to register connector device: -17
Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Tested-by: Darren Etheridge <detheridge@ti.com>
Cc: <stable@vger.kernel.org> #v3.9+
Signed-off-by: Dave Airlie <airlied@redhat.com>

Add a drm_sysfs_connector_remove call when we destroy the panel to make
sure the connector node in sysfs gets deleted.

This is required for proper unload and re-load of this driver as a
module. Without this, we would get a warning at re-load time like so:

   ------------[ cut here ]------------
   WARNING: CPU: 0 PID: 824 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x54/0x74()
   sysfs: cannot create duplicate filename '/class/drm/card0-LVDS-1'
   Modules linked in: [...]
   CPU: 0 PID: 824 Comm: modprobe Not tainted 3.15.0-rc4-00027-g6484f96-dirty #81
   [<c0013bb8>] (unwind_backtrace) from [<c0011824>] (show_stack+0x10/0x14)
   [<c0011824>] (show_stack) from [<c0034e8c>] (warn_slowpath_common+0x68/0x88)
   [<c0034e8c>] (warn_slowpath_common) from [<c0034edc>] (warn_slowpath_fmt+0x30/0x40)
   [<c0034edc>] (warn_slowpath_fmt) from [<c01243f4>] (sysfs_warn_dup+0x54/0x74)
   [<c01243f4>] (sysfs_warn_dup) from [<c0124708>] (sysfs_do_create_link_sd.isra.2+0xb0/0xb8)
   [<c0124708>] (sysfs_do_create_link_sd.isra.2) from [<c02ae37c>] (device_add+0x338/0x520)
   [<c02ae37c>] (device_add) from [<c02ae6e8>] (device_create_groups_vargs+0xa0/0xc4)
   [<c02ae6e8>] (device_create_groups_vargs) from [<c02ae758>] (device_create+0x24/0x2c)
   [<c02ae758>] (device_create) from [<c029b4ec>] (drm_sysfs_connector_add+0x64/0x204)
   [<c029b4ec>] (drm_sysfs_connector_add) from [<bf0b1fec>] (panel_modeset_init+0xb8/0x134 [tilcdc])
   [<bf0b1fec>] (panel_modeset_init [tilcdc]) from [<bf0b2bf0>] (tilcdc_load+0x214/0x4c0 [tilcdc])
   [<bf0b2bf0>] (tilcdc_load [tilcdc]) from [<c029955c>] (drm_dev_register+0xa4/0x104)
      [ .. snip .. ]
   ---[ end trace b2d09cd9578b0497 ]---
   [drm:drm_sysfs_connector_add] *ERROR* failed to register connector device: -17
Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Tested-by: Darren Etheridge <detheridge@ti.com>
Cc: <stable@vger.kernel.org> #v3.9+
Signed-off-by: Dave Airlie <airlied@redhat.com>

The "flags" parameter of the DRM_IOCTL_MODE_ADDFB2 ioctl must be
propagated and used by the driver.
The only possible value of flags is DRM_MODE_FB_INTERLACED.
Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Reviewed-by: Benjamin GAIGNARD <benjamin.gaignard@st.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

bo->mem.placement is not initialized when ttm_bo_man_get_node is called,
so the flag had no effect at all.

v2: change nouveau and vmwgfx as well
Signed-off-by: Christian König <christian.koenig@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

The VGA arbiter does not allow devices to "own" resources that it
doesn't "decode".  However, it does allow devices to "lock" resources
that it doesn't decode.  This gets us into trouble because locking
the resource goes through the same bridge routing updates regardless
of whether we decode the resource.  This means that when a non-decoded
resource is released, the bridge is left with VGA routing enabled and
locking a different device won't clear it.

This happens in the following scenario:

VGA device 01:00.0 (VGA1) is owned by the radeon driver, which
registers a set_vga_decode function which releases legacy VGA decodes.

VGA device 02:00.0 (VGA2) is any VGA device.

VGA1 user locks VGA resources triggering first_use callback of
set_vga_decoded, clearing "decode" and "owns" of legacy resources
on VGA1.

VGA1 user unlocks VGA resources.

VGA2 user locks VGA resources, which skips VGA1 as conflicting as it
does not "own" legacy resources, although VGA routing is still enabled
for the VGA1 bridge.  VGA routing is enabled on VGA2 bridge.

VGA2 may or may not receive VGA transactions depending on the bus
priority of VGA1 vs VGA2 bridge.

To resolve this, we need to allow devices to "own" resources that they
do not "decode".  This way we can track bus ownership of VGA.  When a
device decodes VGA, it only means that we must update the command bits
in cases where the conflicting device is on the same bus.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

* 'drm-next' of git://people.freedesktop.org/~dvdhrm/linux:
  drm/omap: remove null test before kfree
  drm/bochs: replace ALIGN(PAGE_SIZE) by PAGE_ALIGN
  drm/ttm: recognize ARM arch in ioprot handler
  drm: enable render-nodes by default
  drm/ttm: remove declaration of ttm_tt_cache_flush
  drm/gem: remove misleading gfp parameter to get_pages()
  drm/omap: use __GFP_DMA32 for shmem-backed gem
  drm/i915: use shmem helpers if possible

Conflicts:
	drivers/gpu/drm/drm_stub.c

misc core patches picked up by Daniel and Jani.

* tag 'topic/core-stuff-2014-06-30' of git://anongit.freedesktop.org/drm-intel:
  drm/fb-helper: Remove unnecessary list empty check in drm_fb_helper_debug_enter()
  drm/fb-helper: Redundant info->fix.type_aux setting in drm_fb_helper_fill_fix()
  drm/debugfs: add an "edid_override" file per connector
  drm/debugfs: add a "force" file per connector
  drm: add register and unregister functions for connectors
  drm: fix uninitialized acquire_ctx fields (v2)
  drm: Driver-specific ioctls range from 0x40 to 0x9f
  drm: Don't export internal module variables

Pull request of 2014-07-04

* tag 'vmwgfx-next-2014-07-04' of git://people.freedesktop.org/~thomash/linux:
  drm/vmwgfx: Fix compat shader namespace

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: Fabian Frederick <fabf@skynet.be>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

use mm.h definition
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

Nouveau can now be used on ARM, so add an ioprot handler for this
architecture.
Signed-off-by: Lucas Stach <dev@lynxeye.de>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

We introduced render-nodes about 1/2 year ago and no problems showed up.
Remove the drm_rnodes argument and enable them by default now.
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

ttm_tt_cache_flush's implementation was removed in 2009 by commit
c9c97b8c, but its declaration has been hiding in ttm_bo_driver.h since
then.

It has been surviving in the dark for too long now ; give it the mercy
blow.
Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: David 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: David 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: Rob Clark <robdclark@gmail.com>
Tested-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>