- fix problem with pascal and large memory systems
- fix a bunch of MST problems
- fix a runtime PM interaction with MST
Signed-off-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/CACAvsv79O8deSts2fxJ_oS6=q8yA+OgwBSEpp5R=BQBmWa+oyg@mail.gmail.com

Fixes for 4.18.  The ACP patch is a bit bigger than I would like
at this point, but it should have gone in long ago, it just fell
through the cracks.  The others are pretty small and straight-forward.
- ACP fix for boards with 2 I2S instances
- DP fix for CZ, vega
- Fix for a hybrid graphics laptop
- Fix a resume regression
Signed-off-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180718162603.2747-1-alexander.deucher@amd.com

This was causing problems on a system with a large amount of RAM, where
display push buffers were being fetched incorrectly when placed in high
system memory addresses.

While this commit will resolve the issue on that particular system, the
issue will be avoided completely with another patch to more fully solve
problems with display and large amounts of system memory on Pascal.

It's still probably a good idea to disable this to prevent weird issues
in the future.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Creating two I2S instances for Stoney/cz platforms.

v2: squash in:
"drm/amdgpu/acp: Fix slab-out-of-bounds in mfd_add_device in acp_hw_init"
From Daniel Kurtz <djkurtz@chromium.org>.
Signed-off-by: NVijendar Mukunda <Vijendar.Mukunda@amd.com>
Signed-off-by: NAkshu Agrawal <akshu.agrawal@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

Needs ATPX rather than _PR3.

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=200517Reviewed-by: NJunwei Zhang <Jerry.Zhang@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

[why] dp hbr2 eye diagram pattern for raven asic is not stabled.
workaround is to use tp4 pattern. But this should not be
applied to asic before raven.

[how] add new bool varilable in asic caps. for raven asic,
use the workaround. for carrizo, vega, do not use workaround.
Signed-off-by: NHersen Wu <hersenxs.wu@amd.com>
Reviewed-by: NHarry Wentland <Harry.Wentland@amd.com>
Acked-by: NLeo Li <sunpeng.li@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

Fixes: 2c773de2 (drm/amdgpu: defer test IBs on the rings at boot (V3))
Signed-off-by: NLeo Liu <leo.liu@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

Currently nouveau doesn't actually expose the state debugfs file that's
usually provided for any modesetting driver that supports atomic, even
if nouveau is loaded with atomic=1. This is due to the fact that the
standard debugfs files that DRM creates for atomic drivers is called
when drm_get_pci_dev() is called from nouveau_drm.c. This happens well
before we've initialized the display core, which is currently
responsible for setting the DRIVER_ATOMIC cap.

So, move the atomic option into nouveau_drm.c and just add the
DRIVER_ATOMIC cap whenever it's enabled on the kernel commandline. This
shouldn't cause any actual issues, as the atomic ioctl will still fail
as expected even if the display core doesn't disable it until later in
the init sequence. This also provides the added benefit of being able to
use the state debugfs file to check the current display state even if
clients aren't allowed to modify it through anything other than the
legacy ioctls.

Additionally, disable the DRIVER_ATOMIC cap in nv04's display core, as
this was already disabled there previously.
Signed-off-by: NLyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

This both uses the legacy modesetting structures in a racy manner, and
additionally also doesn't even check the right variable (enabled != the
CRTC is actually turned on for atomic).

This fixes issues on my P50 regarding the dedicated GPU not entering
runtime suspend.
Signed-off-by: NLyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

A CRTC being enabled doesn't mean it's on! It doesn't even necessarily
mean it's being used. This fixes runtime PM leaks on the P50 I've got
next to me.
Signed-off-by: NLyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

When MST and atomic were introduced to nouveau, another structure that
could contain a drm_connector embedded within it was introduced; struct
nv50_mstc. This meant that we no longer would be able to simply loop
through our connector list and assume that nouveau_connector() would
return a proper pointer for each connector, since the assertion that
all connectors coming from nouveau have a full nouveau_connector struct
became invalid.

Unfortunately, none of the actual code that looped through connectors
ever got updated, which means that we've been causing invalid memory
accesses for quite a while now.

An example that was caught by KASAN:

[  201.038698] ==================================================================
[  201.038792] BUG: KASAN: slab-out-of-bounds in nvif_notify_get+0x190/0x1a0 [nouveau]
[  201.038797] Read of size 4 at addr ffff88076738c650 by task kworker/0:3/718
[  201.038800]
[  201.038822] CPU: 0 PID: 718 Comm: kworker/0:3 Tainted: G           O      4.18.0-rc4Lyude-Test+ #1
[  201.038825] Hardware name: LENOVO 20EQS64N0B/20EQS64N0B, BIOS N1EET78W (1.51 ) 05/18/2018
[  201.038882] Workqueue: events nouveau_display_hpd_work [nouveau]
[  201.038887] Call Trace:
[  201.038894]  dump_stack+0xa4/0xfd
[  201.038900]  print_address_description+0x71/0x239
[  201.038929]  ? nvif_notify_get+0x190/0x1a0 [nouveau]
[  201.038935]  kasan_report.cold.6+0x242/0x2fe
[  201.038942]  __asan_report_load4_noabort+0x19/0x20
[  201.038970]  nvif_notify_get+0x190/0x1a0 [nouveau]
[  201.038998]  ? nvif_notify_put+0x1f0/0x1f0 [nouveau]
[  201.039003]  ? kmsg_dump_rewind_nolock+0xe4/0xe4
[  201.039049]  nouveau_display_init.cold.12+0x34/0x39 [nouveau]
[  201.039089]  ? nouveau_user_framebuffer_create+0x120/0x120 [nouveau]
[  201.039133]  nouveau_display_resume+0x5c0/0x810 [nouveau]
[  201.039173]  ? nvkm_client_ioctl+0x20/0x20 [nouveau]
[  201.039215]  nouveau_do_resume+0x19f/0x570 [nouveau]
[  201.039256]  nouveau_pmops_runtime_resume+0xd8/0x2a0 [nouveau]
[  201.039264]  pci_pm_runtime_resume+0x130/0x250
[  201.039269]  ? pci_restore_standard_config+0x70/0x70
[  201.039275]  __rpm_callback+0x1f2/0x5d0
[  201.039279]  ? rpm_resume+0x560/0x18a0
[  201.039283]  ? pci_restore_standard_config+0x70/0x70
[  201.039287]  ? pci_restore_standard_config+0x70/0x70
[  201.039291]  ? pci_restore_standard_config+0x70/0x70
[  201.039296]  rpm_callback+0x175/0x210
[  201.039300]  ? pci_restore_standard_config+0x70/0x70
[  201.039305]  rpm_resume+0xcc3/0x18a0
[  201.039312]  ? rpm_callback+0x210/0x210
[  201.039317]  ? __pm_runtime_resume+0x9e/0x100
[  201.039322]  ? kasan_check_write+0x14/0x20
[  201.039326]  ? do_raw_spin_lock+0xc2/0x1c0
[  201.039333]  __pm_runtime_resume+0xac/0x100
[  201.039374]  nouveau_display_hpd_work+0x67/0x1f0 [nouveau]
[  201.039380]  process_one_work+0x7a0/0x14d0
[  201.039388]  ? cancel_delayed_work_sync+0x20/0x20
[  201.039392]  ? lock_acquire+0x113/0x310
[  201.039398]  ? kasan_check_write+0x14/0x20
[  201.039402]  ? do_raw_spin_lock+0xc2/0x1c0
[  201.039409]  worker_thread+0x86/0xb50
[  201.039418]  kthread+0x2e9/0x3a0
[  201.039422]  ? process_one_work+0x14d0/0x14d0
[  201.039426]  ? kthread_create_worker_on_cpu+0xc0/0xc0
[  201.039431]  ret_from_fork+0x3a/0x50
[  201.039441]
[  201.039444] Allocated by task 79:
[  201.039449]  save_stack+0x43/0xd0
[  201.039452]  kasan_kmalloc+0xc4/0xe0
[  201.039456]  kmem_cache_alloc_trace+0x10a/0x260
[  201.039494]  nv50_mstm_add_connector+0x9a/0x340 [nouveau]
[  201.039504]  drm_dp_add_port+0xff5/0x1fc0 [drm_kms_helper]
[  201.039511]  drm_dp_send_link_address+0x4a7/0x740 [drm_kms_helper]
[  201.039518]  drm_dp_check_and_send_link_address+0x1a7/0x210 [drm_kms_helper]
[  201.039525]  drm_dp_mst_link_probe_work+0x71/0xb0 [drm_kms_helper]
[  201.039529]  process_one_work+0x7a0/0x14d0
[  201.039533]  worker_thread+0x86/0xb50
[  201.039537]  kthread+0x2e9/0x3a0
[  201.039541]  ret_from_fork+0x3a/0x50
[  201.039543]
[  201.039546] Freed by task 0:
[  201.039549] (stack is not available)
[  201.039551]
[  201.039555] The buggy address belongs to the object at ffff88076738c1a8
                                 which belongs to the cache kmalloc-2048 of size 2048
[  201.039559] The buggy address is located 1192 bytes inside of
                                 2048-byte region [ffff88076738c1a8, ffff88076738c9a8)
[  201.039563] The buggy address belongs to the page:
[  201.039567] page:ffffea001d9ce200 count:1 mapcount:0 mapping:ffff88084000d0c0 index:0x0 compound_mapcount: 0
[  201.039573] flags: 0x8000000000008100(slab|head)
[  201.039578] raw: 8000000000008100 ffffea001da3be08 ffffea001da25a08 ffff88084000d0c0
[  201.039582] raw: 0000000000000000 00000000000d000d 00000001ffffffff 0000000000000000
[  201.039585] page dumped because: kasan: bad access detected
[  201.039588]
[  201.039591] Memory state around the buggy address:
[  201.039594]  ffff88076738c500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[  201.039598]  ffff88076738c580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[  201.039601] >ffff88076738c600: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
[  201.039604]                                                  ^
[  201.039607]  ffff88076738c680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  201.039611]  ffff88076738c700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  201.039613] ==================================================================
Signed-off-by: NLyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Cc: Karol Herbst <karolherbst@gmail.com>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Every codepath in nouveau that loops through the connector list
currently does so using the old method, which is prone to race
conditions from MST connectors being created and destroyed. This has
been causing a multitude of problems, including memory corruption from
trying to access connectors that have already been freed!
Signed-off-by: NLyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Cc: Karol Herbst <karolherbst@gmail.com>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

The bo array has req->nr_buffers elements so the > should be >= so we
don't read beyond the end of the array.

Fixes: a1606a95 ("drm/nouveau: new gem pushbuf interface, bump to 0.0.16")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

It was possible for this to be skipped when shutting down MST streams, and
leaving the core channel interlocked with a wndw channel update that never
happens - leading to a hung display.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>
Tested-By: NLyude Paul <lyude@redhat.com>

Merge tag 'drm-intel-fixes-2018-07-12' of git://anongit.freedesktop.org/drm/drm-intel into drm-fixes

I already pulled the first fix, pull the GVT fixes.

- GVT fix for KBL vGPU hang to update virtual register from LRI.
Signed-off-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180713070922.GA19840@intel.com

Two armada fixes.
Signed-off-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180713075427.GA16160@rmk-PC.armlinux.org.uk

Fixes for v4.18-rc5:
- Single fix for a build error when the driver is builtin,
  but the backend is a loadable module.
Signed-off-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/9c596cf5-3f24-070e-74f2-c59bfbaf68fa@linux.intel.com

drm/tegra: Fixes for v4.18-rc5

This contains a couple of one- or two-line fixes for various minor
issues in the Tegra driver.
Signed-off-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180712070142.15571-1-thierry.reding@gmail.com

A few display and GPUVM fixes for 4.18.

A few more fixes for 4.18. Two display fixes and a fix to avoid a segfault if
the GPU does not power up properly on resume.  These are on top of my pull
from earlier this week.
Signed-off-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180712043820.2877-1-alexander.deucher@amd.com

Merge tag 'drm-intel-fixes-2018-07-10' of git://anongit.freedesktop.org/drm/drm-intel into drm-fixes

- Fix hotplug irq ack on i965/g4x (Ville)
Signed-off-by: NDave Airlie <airlied@redhat.com>

Link: https://patchwork.freedesktop.org/patch/msgid/20180710213249.GA16479@intel.com

Rather than using the index variable stored in vram.  If
the device fails to come back online after a resume cycle,
reads from vram will return all 1s which will cause a
segfault. Based on a patch from Thomas Martitz <kugel@rockbox.org>.
This avoids the segfault, but we still need to sort out
why the GPU does not come back online after a resume.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=105760Acked-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

[Why]
When a dce100 asic was suspended, the clocks were not set to 0.
Upon resume, the new clock was compared to the existing clock,
they were found to be the same, and so the clock was not set.
This resulted in a pernicious blackscreen.

[How]
In atomic commit, check to see if there are any active pipes.
If no, set clocks to 0
Signed-off-by: NDavid Francis <David.Francis@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

The driver is expecting clock frequency in kHz, while SMU returns
the values in 10kHz, which causes the bandwidth validation to fail

4.18 has the faulty clock assignment in pp_to_dc_clock_levels_with_latency
only, which is only used by Vega. Make sure we multiply these values
by 10 here, as we do for other ASICs as powerplay assigned them
wrong. 4.19 has the proper fix in powerplay.

v2: Add Fixes tag
v3: Fixes -> Bugzilla, with simplified link

Bugzilla: https://bugs.freedesktop.org/107082Signed-off-by: NMikita Lipski <mikita.lipski@amd.com>
Signed-off-by: NHarry Wentland <harry.wentland@amd.com>
Acked-by: NMichel Dänzer <michel.daenzer@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

gvt-fixes-2018-07-11

- Fix KBL virtual register update from LRI for GPU hang (Henry)
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180711024056.GV1267@zhen-hp.sh.intel.com

Problem: When PD/PT update made by CPU root PD was not yet mapped causing
page fault.

Fix: Verify root PD is mapped into CPU address space.

v2:
Make sure that we add the root PD to the relocated list
since then it's get mapped into CPU address space bt default
in amdgpu_vm_update_directories.

v3:
Drop change to not move kernel type BOs to evicted list.

v4:
Remove redundant bo move to relocated list.

Link: https://bugs.freedesktop.org/show_bug.cgi?id=107065Signed-off-by: NAndrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NJunwei Zhang <Jerry.Zhang@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Otherwise we try to program hardware with the wrong watermark functions
when multiple DCE generations are installed in one system.
Signed-off-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NHarry Wentland <harry.wentland@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Without this, there could not be enough slots, which could trigger the
BUG_ON in reservation_object_add_shared_fence.

v2:
* Jump to the error label instead of returning directly (Jerry Zhang)
v3:
* Reserve slots for command submission after VM updates (Christian König)

Cc: stable@vger.kernel.org
Bugzilla: https://bugs.freedesktop.org/106418
Reported-by: mikhail.v.gavrilov@gmail.com
Signed-off-by: NMichel Dänzer <michel.daenzer@amd.com>
Signed-off-by: NJunwei Zhang <Jerry.Zhang@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

This reverts commit 018d82e5.

This breaks DDC in certain cases.  Revert for 4.18 and previous kernels.
For 4.19, this is fixed with the following more extensive patches:
drm/amd/display: Serialize is_dp_sink_present
drm/amd/display: Break out function to simply read aux reply
drm/amd/display: Return aux replies directly to DRM
drm/amd/display: Right shift AUX reply value sooner than later
drm/amd/display: Read AUX channel even if only status byte is returned

Link: https://lists.freedesktop.org/archives/amd-gfx/2018-July/023788.htmlAcked-by: NHarry Wentland <harry.wentland@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Cast *tmp* and *nb_base* to u64 in order to give the compiler
complete information about the proper arithmetic to use.

Notice that such variables are used in contexts that expect
expressions of type u64 (64 bits, unsigned) and the following
expressions are currently being evaluated using 32-bit arithmetic:

tmp << 25
nb_base << 25

Addresses-Coverity-ID: 200586 ("Unintentional integer overflow")
Addresses-Coverity-ID: 200587 ("Unintentional integer overflow")
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Use new return type vm_fault_t for fault handler. For now,
this is just documenting that the function returns a
VM_FAULT value rather than an errno. Once all instances are
converted, vm_fault_t will become a distinct type.

Ref-> commit 1c8f4220 ("mm: change return type to
vm_fault_t") was added in 4.17-rc1 to introduce the new
typedef vm_fault_t. Currently we are making change to all
drivers to return vm_fault_t for page fault handlers. As
part of that char/agp driver is also getting changed to
return vm_fault_t type from fault handler.
Signed-off-by: NSouptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: NMatthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Mail to dri-devel went out, linux-next was updated, but we forgot this
one here.

Cc: David Airlie <airlied@linux.ie>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Acked-by: NAlex Deucher <alexander.deucher@amd.com>
Acked-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180706072842.9009-1-daniel.vetter@ffwll.ch

Lucas wrote:
"a couple of small fixes:
- 2 patches from Fabio to fix module reloading
- one patch to fix a userspace visible regression, where the job
timeout is a bit too eager and kills legitimate jobs"
Signed-off-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1530868450.15725.8.camel@pengutronix.de

Just like with PIPESTAT, the edge triggered IIR on i965/g4x
also causes problems for hotplug interrupts. To make sure
we don't get the IIR port interrupt bit stuck low with the
ISR bit high we must force an edge in ISR. Unfortunately
we can't borrow the PIPESTAT trick and toggle the enable
bits in PORT_HOTPLUG_EN as that act itself generates hotplug
interrupts. Instead we just have to loop until we've cleared
PORT_HOTPLUG_STAT, or we just give up and WARN.

v2: Don't frob with PORT_HOTPLUG_EN

Cc: stable@vger.kernel.org
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180614175625.1615-1-ville.syrjala@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>
(cherry picked from commit 0ba7c51a)
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>

Add the missing locks to the IRQ enable/disable paths, and fix a comment
in the interrupt handler: reading the ISR clears down the status bits,
but does not reset the interrupt so it can signal again.  That seems to
require a write.
Signed-off-by: NRussell King <rmk+kernel@armlinux.org.uk>

The colorkey mode property was not correctly disabling the colorkeying
when "disabled" mode was selected.  Arrange for this to work as one
would expect.
Signed-off-by: NRussell King <rmk+kernel@armlinux.org.uk>

Here we are checking for the buffer length, not an offset for writing
to, so using > is correct. The current code incorrectly rejects a
command buffer ending at the memory buffer's end.
Signed-off-by: NMikko Perttunen <mperttunen@nvidia.com>
Reviewed-by: NDmitry Osipenko <digetx@gmail.com>
Signed-off-by: NThierry Reding <treding@nvidia.com>

Only gather pins are mapped by the Host1x driver, regular BO relocations
are not. Check whether size of unpin isn't 0, otherwise IOVA allocation at
0x0 could be erroneously released.
Signed-off-by: NDmitry Osipenko <digetx@gmail.com>
Signed-off-by: NThierry Reding <treding@nvidia.com>

Host1x's CDMA can't access the command buffers if IOMMU and Host1x
firewall are enabled in the kernels config because firewall doesn't map
the copied buffer into IOVA space. Fix this by skipping IOMMU
initialization if firewall is enabled as firewall merges sparse cmdbufs
into a single contiguous buffer and hence IOMMU isn't needed in this case.
Signed-off-by: NDmitry Osipenko <digetx@gmail.com>
Signed-off-by: NThierry Reding <treding@nvidia.com>

When the base sun4i DRM driver is built-in but the back-end is
a loadable module, we run into a link error:

drivers/gpu/drm/sun4i/sun4i_drv.o: In function `sun4i_drv_probe':
sun4i_drv.c:(.text+0x60c): undefined reference to `sun4i_frontend_of_table'

The dependency is a bit tricky, the best workaround I have come up
with is to use a Makefile hack to to interpret both
CONFIG_DRM_SUN4I_BACKEND=m and CONFIG_DRM_SUN4I_BACKEND=y
as a directive to build the front-end the same way as the main module.

Fixes: dd0421f4 ("drm/sun4i: Add a driver for the display frontend")
Link: https://lore.kernel.org/lkml/20180301091908.zcptz3ezqr2c6ly5@flea/Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NMaxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180706142847.2032381-1-arnd@arndb.de