Using calloc() instead of malloc() as preventive measure, so there
never can be any hidden bugs or leaks due uninitialized memory.
The extra cost of using this compiler intrinsic should be practically
impossible to measure - in many cases a good compiler can even deduce
if certain areas really don't need to be zero'd (because they're written
to right after allocation) and create more efficient machine code.
The code pathes in question are pretty cold anyways, so it's probably
not worth even thinking about potential extra runtime costs.
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
No need for complicated wrapping/unwrapping: it's always just
miCreateResources() anyway - so we can call it directly.
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Found by clang 19.1.7:
hw/xfree86/drivers/modesetting/driver.c:163:21:
warning: initializer overrides prior initialization of this subobject
[-Winitializer-overrides]
163 | ._modinfo1_ = MODINFOSTRING2,
| ^~~~~~~~~~~~~~
hw/xfree86/drivers/modesetting/driver.c:162:21:
note: previous initialization is here
162 | ._modinfo1_ = MODINFOSTRING1,
| ^~~~~~~~~~~~~~
Fixes: 2a10eff6c ("xfree86: modsetting: use explicit field initializers for XF86ModuleData")
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1910>
Even though the order of these fields shouldn't change anytime
soon, it's still better programming style to name'em explicitly.
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1788>
The symbol controls whether to include dix-config.h, and it's always set,
thus we don't need it (and dozens of ifdef's) anymore.
This commit only removes them from our own source files, where we can
guarantee that dix-config.h is present - leaving the (potentially exported)
headers untouched.
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
This has been nothing but an alias for two decades now (somewhere in R6.6),
so there doesn't seem to be any practical need for this indirection.
The macro still needs to remain, as long as (external) drivers still using it.
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1529>
Clears -Wcalloc-transposed-args warnings from gcc 14.1, such as:
../dix/main.c:165:42: warning: ‘calloc’ sizes specified with ‘sizeof’ in the
earlier argument and not in the later argument [-Wcalloc-transposed-args]
165 | serverClient = calloc(sizeof(ClientRec), 1);
| ^~~~~~~~~
../dix/main.c:165:42: note: earlier argument should specify number of
elements, later size of each element
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1606>
A clip should represent the area that is covering the current FB associated
with the CRTC. So making sure each input rect covers any area in the FB is
the first thing to do. If that is the case, the size and coordinates should
be adjusted based on the partial area in the FB the each rect covers. The size
elements need to be truncated if the rect's size exceeds FB's for the CRTC.
Then offsets should be applied to coordinates if the CRTC's offsets aren't 0.
And coordinate transposing and inversion are needed in case the rotated image
is assigned to the FB.
Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
TearFree support has been available in the modesetting driver for a year
with no issues reported. The code is mature and robust, with error handling
that's been vetted across many hardware configurations.
Notably, TearFree is also the only way to achieve a tear-free desktop with
mismatched displays and transformed CRTCs.
Enable TearFree by default for a smooth desktop experience out of the box.
Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Try to minimize the used hw cursor size in order to
minimize power consumption. There is no kernel query
for the minimum so we'll just probe around with
setcursor2 (using an invisible cursor image so
there will be no visual artifacts).
To avoid having to deal with absolutely every size stick
to power-of-two numbers. And with a bit of extra effort
we can determine whether non-square dimesions will also
work, which they do to some degree on current Intel GPUs.
On my Alderlake laptop I'm seeing a massive (up to .5W)
difference in power consumption between 64x64 vs. 256x256
cursors. While some of that is undoubtedly something that
needs to be fixed in i915's display data buffer allocation
code, it still makes sense to use as small as possible
cursor to minimize the wastege.
In case the crtc is rotated just punt to the max cursor size
for now since midlayer has already done the coordinate
transformations based on that. To make smaller cursors work
with rotation we'd either need to make the midlayer(s) aware
of the final cursor size, or just handle the whole roation
business in modesetting. I suspect the latter option would
be easier.
v2: Only allow square cursors in most cases for now as eg.
on modern Intel hardware non-square only works with
wide+short but not with narrow+tall cursors. Non-square
size may still be used when maximum limits aren't
square and the squared+POT'd dimensions would exceed
one of the max limits.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
When using TearFree, DRI clients have no way of accurately knowing when
their copied pixmaps appear on the display without utilizing the kernel
driver's notification indicating that the TearFree flip containing their
pixmap is complete. This is because the target CRTC's MSC can change while
the predicted completion MSC is calculated and even while the page flip
IOCTL is sent to the kernel due to scheduling delays and/or unfortunate
timing. Even worse, a page flip isn't actually guaranteed to be finished
after one vblank; it may be several MSCs until a flip actually finishes
depending on delays and load in hardware.
As a result, DRI clients may be off by one or more MSCs when they naively
expect their pixmaps to be visible at MSC+1 with TearFree enabled. This,
for example, makes it impossible for DRI clients to achieve precise A/V
synchronization when TearFree is enabled.
This change therefore adds a way for DRI clients to receive a notification
straight from the TearFree flip-done handler to know exactly when their
pixmaps appear on the display. This is done by checking for a NULL pixmap
pointer to modesetting's DRI flip routine, which indicates that the DRI
client has copied its pixmap and wants TearFree to send a notification when
the copied pixmap appears on the display as part of a TearFree flip. The
existing PageFlip scaffolding is reused to achieve this with minimal churn.
The Present extension will be updated in an upcoming change to utilize this
new mechanism for DRI clients' presentations.
Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Acked-by: Martin Roukala <martin.roukala@mupuf.org>
There is more than one place with the confusing TearFree state check for a
CRTC. Instead of open-coding the TearFree check everywhere, introduce a
helper, ms_tearfree_is_active_on_crtc, to cover the TearFree state checks.
Suggested-by: Martin Roukala <martin.roukala@mupuf.org>
Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Reviewed-by: Martin Roukala <martin.roukala@mupuf.org>
If atomic modesetting is to be enabled in the configuration file, log
whether this is supported and eventually enabled or disabled.
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Reviewed-by: Martin Roukala <martin.roukala@mupuf.org>
This adds support for TearFree page flips to eliminate tearing without the
use of a compositor. It allocates two shadow buffers for each CRTC, a back
buffer and a front buffer, and uses damage tracking to minimize excessive
copying between buffers and skip unnecessary flips when the screen's
contents remain unchanged. It works on transformed screens too, such as
rotated and scaled CRTCs.
When PageFlip is enabled, TearFree won't force fullscreen DRI clients to
synchronize their page flips to the vblank interval.
TearFree is disabled by default.
Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Rotation is broken for all drm drivers not providing hardware rotation
support. Drivers that give direct access to vram and not needing dirty
updates still work but only by accident. The problem is caused by
modesetting not sending the correct fb_id to drmModeDirtyFB() and
passing the damage rects in the rotated state and not as the crtc
expects them. This patch takes care of both problems.
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
Whenever an unredirected fullscreen window uses pageflipping for a
DRI3/Present PresentPixmap() operation and the X-Screen has more than
one active output, multiple crtc's need to execute pageflips. Only
after the last flip has completed can the PresentPixmap operation
as a whole complete.
If a sync_flip is requested for the present, then the current
implementation will synchronize each pageflip to the vblank of
its associated crtc. This provides tear-free image presentation
across all outputs, but introduces a different artifact, if not
all outputs run at the same refresh rate with perfect synchrony:
The slowest output throttles the presentation rate, and present
completion is delayed to flip completion of the "latest" output
to complete. This means degraded performance, e.g., a dual-display
setup with a 144 Hz monitor and a 60 Hz monitor will always be
throttled to at most 60 fps. It also means non-constant present
rate if refresh cycles drift against each other, creating complex
"beat patterns", tremors, stutters and periodic slowdowns - quite
irritating!
Such a scenario will be especially annoying if one uses multiple
outputs in "mirror mode" aka "clone mode". One output will usually
be the "production output" with the highest quality and fastest
display attached, whereas a secondary mirror output just has a
cheaper display for monitoring attached. Users care about perfect
and perfectly timed tear-free presentation on the "production output",
but cares less about quality on the secondary "mirror output". They
are willing to trade quality on secondary outputs away in exchange
for better presentation timing on the "production output".
One example use case for such production + monitoring displays are
neuroscience / medical science applications where one high quality
display device is used to present visual animations to test subjects
or patients in a fMRI scanner room (production display), whereas
an operator monitors the same visual animations from a control room
on a lower quality display. Presentation timing needs to be perfect,
and animations high-speed and tear-free for the production display,
whereas quality and timing don't matter for the monitoring display.
This commit gives users the option to choose such a trade-off as
opt-in:
It adds a new boolean option "AsyncFlipSecondaries" to the device section
of xorg.conf. If this option is specified as true, then DRI3 pageflip
behaviour changes as follows:
1. The "reference crtc" for a windows PresentPixmap operation does a
vblank synced flip, or a DRM_MODE_PAGE_FLIP_ASYNC non-synchronized
flip, as requested by the caller, just as in the past. Typically
flips will be requested to be vblank synchronized for tear-free
presentation. The "reference crtc" is the one chosen by the caller
to drive presentation timing (as specified by PresentPixmap()'s
"target_msc", "divisor", "remainder" parameters and implemented by
vblank events) and to deliver Present completion timestamps (msc
and ust) extracted from its pageflip completion event.
2. All other crtc's, which also page-flip in a multi-display configuration,
will try to flip with DRM_MODE_PAGE_FLIP_ASYNC, ie. immediately and
not synchronized to vblank. This allows the PresentPixmap operation
to complete with little delay compared to a single-display present,
especially if the different crtc's run at different video refresh
rates or their refresh cycles are not perfectly synchronized, but
drift against each other. The downside is potential tearing artifacts
on all outputs apart from the one of the "reference crtc".
Successfully tested on a AMD gpu with single-display, dual-display and
triple-display setups, and with single-X-Screen as well as dual-X-Screen
"ZaphodHeads" configurations.
Please consider merging this commit for the upcoming server 1.21 branch.
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
When using DRI3+Present with PRIME render offload, sometimes there is
a mismatch between the stride of the to-be-presented Pixmap and the
frontbuffer. The current code would reject a pageflip present in this
case if atomic modesetting is not enabled, ie. always, as atomic
modesetting is disabled by default due to brokeness in the current
modesetting-ddx.
Fullscreen presents without page flipping however trigger the copy
path as fallback, which causes not only unreliable presentation timing
and degraded performance, but also massive tearing artifacts due to
rendering to the framebuffer without any hardware sync to vblank.
Tearing is extra awful on modesetting-ddx because glamor afaics seems
to use drawing of a textured triangle strip for the copy implementation,
not a dedicated blitter engine. The rasterization pattern creates extra
awful tearing artifacts.
We can do better: According to a tip from Michel Daenzer (thanks!),
at least atomic modesetting capable kms drivers should be able to
reliably change scanout stride during a pageflip, even if atomic
modesetting is not actually enabled for the modesetting client.
This commit adds detection logic to find out if the underlying kms
driver is atomic_modeset_capable, and if so, it no longer rejects
page flip presents on mismatched stride between new Pixmap and
frontbuffer.
We (ab)use a call to drmSetClientCap(ms->fd, DRM_CLIENT_CAP_ATOMIC, 0);
for this purpose. The call itself has no practical effect, as it
requests disabling atomic mode, although atomic mode is disabled by
default. However, the return value of drmSetClientCap() tells us if the
underlying kms driver is atomic modesetting capable: An atomic driver
will return 0 for success. A legacy non-atomic driver will return a
non-zero error code, either -EINVAL for early atomic Linux versions
4.0 - 4.19 (or for non-atomic Linux 3.x and earlier), or -EOPNOTSUPP
for Linux 4.20 and later.
Testing on a MacBookPro 2017 with Intel Kabylake display server gpu +
AMD Polaris11 as prime renderoffload gpu, X-Server master + Mesa 21.0.3
show improvement from unbearable tearing to perfect, despite a stride
mismatch between display gpu and Pixmap of 11776 Bytes vs. 11520
Bytes. That this is correct behaviour was also confirmed by comparing the
behaviour and .check_flip implementation of the patched modesetting-ddx
against the current intel-ddx SNA Present implementation.
Please consider merging this patch before the server-1.21 branch point.
This patch could also be cherry-picked into the server 1.20 branch to
fix the same limitation.
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
A misplaced error check can cause this failure scenario, and does
so reliably as tested on Ubuntu 21.04 with KDE Plasma 5 desktop
within the first few seconds of login session startup, rendering
VRR under modesetting-ddx unusable:
1. Some X11 client application changes some window property.
2. ms_change_property() is called as part of the property change
handling call chain (client->requestVector[X_ChangeProperty]).
It removes itself temporarily from the call chain - or so it
thinks, hooking up saved_change_property instead.
3. ret = saved_change_property(client) is called and fails
temporarily for some non-critical reason.
4. The misplaced error check returns early (error abort), without
first restoring ms_change_property() as initial X_ChangeProperty
handler in the call chain again.
-> Now ms_change_property() has removed itself permanently from the
property handler call chain for the remainder of the X session
and VRR property changes on windows are no longer handled, ie.
VRR no longer gets enabled/disabled in response to window VRR
property changes.
Place the error check at the proper place, just as it is correctly
done by amdgpu-ddx, and in modesetting-ddx ms_delete_property()
function.
Verified to fix VRR handling with an AMD gpu under KDE desktop
session.
Please consider merging before branching the server 1.21 branch.
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
This mode for displays running on evdi/udl as side effect of failed glamor_egl_init
reverse_prime_offload_mode was initialized to FALSE
After Mesa upgrade to 21.0.0 GL_RENDERER is not llvmpipe that results in successful glamor_egl_init
and reverse_prime_offload_mode enabled.
This commit is explicitly disabling reverse_prime_offload_mode for evdi and udl drivers
Signed-off-by: Łukasz Spintzyk <lukasz.spintzyk@synaptics.com>
If the kernel exposes GAMMA_LUT and GAMMA_LUT_SIZE properties and the size is
not what the server has pre-configured for the crtc, free the old gamma ramp
memory allocated by the server and replace it with new allocations of the
appropriate size.
In addition, when GAMMA_LUT is available, use drmModeCreatePropertyBlob() and
drmModeObjectSetProperty() to set the gamma ramp rather than using the legacy
drmModeCrtcSetGamma() function.
Add a new option "UseGammaLUT" to allow disabling this new behavior and falling
back to drmModeCrtcSetGamma() unconditionally.
Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
There was a time when setting a mode on a CRTC would not depend on the
associated connector's state. If a mode had been set successfully once,
it would mean it would work later on.
This changed with the introduction of new connectors type that now
require a link training sequence (DP, HDMI 2.0), and that means that
some events may have happened while the X server was not master that
would then prevent the mode from successfully be restored to its
previous state.
This patch relaxes the requirement that all modes should be restored on
EnterVT, or the entire X-Server would go down by allowing modesets to
fail (with some warnings). If a modeset fails, the CRTC will be
disabled, and a RandR event will be sent for the desktop environment to
fix the situation as well as possible.
Additional patches might be needed to make sure that the user would
never be left with all screens black in some scenarios.
v2 (Martin Peres):
- whitespace fixes
- remove the uevent handling (it is done in a previous patch)
- improve the commit message
- reduce the size of the patch by not changing lines needlessly
- return FALSE if one modeset fails in ignore mode
- add comments/todos to explain why we do things
- disable the CRTCs that failed the modeset
Signed-off-by: Kishore Kadiyala <kishore.kadiyala@intel.com>
Signed-off-by: Martin Peres <martin.peres@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Kishore Kadiyala <kishore.kadiyala@intel.com>
Closes: #1010
Normally, we would receive a uevent coming from Linux's DRM subsystem,
which would trigger the check for disappearing/appearing resources.
However, this event is not received when X is not master (another VT
is selected), and so the userspace / desktop environment would not be
notified about the changes that happened while X wasn't master.
To fix the issue, this patch forces a refresh on EnterVT by splitting
the kms-checking code from the uevent handling into its own (exported)
function called drmmode_update_kms_state. This function is then called
from both the uevent-handling function, and on EnterVT right before
restoring the modes.
Signed-off-by: Martin Peres <martin.peres@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Kishore Kadiyala <kishore.kadiyala@intel.com>
Tested-by: Kishore Kadiyala <kishore.kadiyala@intel.com>
Fetch VariableRefresh option value from X conf file for
modesetting backend DDX driver. This option defaults to false,
and must be set to "true" in conf file for variable refresh
support in the DDX driver.
Signed-off-by: Uday Kiran Pichika <pichika.uday.kiran@intel.com>
Window wrappers gets the notification when the window
properties changes. These wrappers are mainly used to
keep track of per-window _VARIABLE_REFRESH property values.
These changes have been ported from AMDGPU
Signed-off-by: Uday Kiran Pichika <pichika.uday.kiran@intel.com>
These changes have been ported from AMD GPU DDX driver.
This patch adds support for setting the CRTC variable refresh property
for suitable windows flipping via the Present extension.
In order for a window to be suitable for variable refresh it must have
the _VARIABLE_REFRESH property set by the MESA and inform Modesetting
DDX driver with window property updates.
Then the window must pass the checks required to be suitable for
Present extension flips - it must cover the entire X screen and no
other window may already be flipping. And also DRM connector should
be VRR capable.
With these conditions met every CRTC for the X screen will have their
variable refresh property set to true.
Kernel Changes to support this feature in I915 driver is under development.
Tested with DOTA2, Xonotic and custom GLX apps.
Signed-off-by: Uday Kiran Pichika <pichika.uday.kiran@intel.com>
Most (but not all) of these were found by using
codespell --builtin clear,rare,usage,informal,code,names
but not everything reported by that was fixed.
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Calling rrGetScrPriv when RandR isn't initialized causes an assertion
failure that aborts the server:
Xorg: ../include/privates.h:121: dixGetPrivateAddr: Assertion `key->initialized' failed.
Thread 1 "Xorg" received signal SIGABRT, Aborted.
0x00007ffff78a8f25 in raise () from /usr/lib/libc.so.6
(gdb) bt
#0 0x00007ffff78a8f25 in raise () from /usr/lib/libc.so.6
#1 0x00007ffff7892897 in abort () from /usr/lib/libc.so.6
#2 0x00007ffff7892767 in __assert_fail_base.cold () from /usr/lib/libc.so.6
#3 0x00007ffff78a1526 in __assert_fail () from /usr/lib/libc.so.6
#4 0x00007ffff7fb57c1 in dixGetPrivateAddr (privates=0x555555ab1b60, key=0x555555855720 <rrPrivKeyRec>) at ../include/privates.h:121
#5 0x00007ffff7fb5822 in dixGetPrivate (privates=0x555555ab1b60, key=0x555555855720 <rrPrivKeyRec>) at ../include/privates.h:136
#6 0x00007ffff7fb586a in dixLookupPrivate (privates=0x555555ab1b60, key=0x555555855720 <rrPrivKeyRec>) at ../include/privates.h:166
#7 0x00007ffff7fb8445 in CreateScreenResources (pScreen=0x555555ab1790) at ../hw/xfree86/drivers/modesetting/driver.c:1335
#8 0x000055555576c5e4 in xf86CrtcCreateScreenResources (screen=0x555555ab1790) at ../hw/xfree86/modes/xf86Crtc.c:744
#9 0x00005555555d8bb6 in dix_main (argc=4, argv=0x7fffffffead8, envp=0x7fffffffeb00) at ../dix/main.c:214
#10 0x00005555557a4f0b in main (argc=4, argv=0x7fffffffead8, envp=0x7fffffffeb00) at ../dix/stubmain.c:34
This can happen, for example, if the server is configured with Xinerama
and there is more than one X screen:
Section "ServerLayout"
Identifier "crash"
Screen 0 "modesetting"
Screen 1 "dummy" RightOf "modesetting"
Option "Xinerama"
EndSection
Section "Device"
Identifier "modesetting"
Driver "modesetting"
EndSection
Section "Screen"
Identifier "modesetting"
Device "modesetting"
EndSection
Section "Device"
Identifier "dummy"
Driver "dummy"
EndSection
Section "Screen"
Identifier "dummy"
Device "dummy"
EndSection
The problem does not reproduce if there is only one X screen because of
this code in xf86RandR12Init:
#ifdef PANORAMIX
/* XXX disable RandR when using Xinerama */
if (!noPanoramiXExtension) {
if (xf86NumScreens == 1)
noPanoramiXExtension = TRUE;
else
return TRUE;
}
#endif
Fix the problem by checking dixPrivateKeyRegistered(rrPrivKey) before
calling rrGetScrPriv. This is similar to what the xf86-video-amdgpu
driver does:
fd66f5c0be/src/amdgpu_kms.c (L388)
Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Commit cb1b1e184 modified msSharePixmapBacking() to derive modesettingPtr from
the 'screen' argument. Unfortunately, the name of the argument is misleading --
the screen is the slave screen. If the master is modesetting,
and the slave is not modesetting, it will segfault.
To fix the problem, this change derives modesettingPtr from
ppix->drawable.pScreen. This method is already used when calling
ms->glamor.shareable_fd_from_pixmap() later in the function.
To avoid future issues, this change also renames the 'screen' argument to
'slave'.
Signed-off-by: Alex Goins <agoins@nvidia.com>
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
New now ask Glamor to use EGL_MESA_query_driver to obtain the DRI driver
name; if successful, we use that as the DRI driver name. Following the
existing dri2.c logic, we also use the same name for the VDPAU driver,
except for i965 (and now iris), where we switch to the "va_gl" fallback.
This allows us to bypass the PCI ID lists in xserver and centralize the
driver selection mechanism inside Mesa. The hope is that we no longer
have to update these lists for any future hardware.
Now that we've fixed LoaderSymbolFromModule this should work properly.
This reverts commit 5c7c6d5cff.
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Move from the xf86 specific ScrnInfoRec::privates, to the dix private
handling. Since there's no FreeScreen function in ScreenPtr, fold the
former within the existing CloseScreen.
Users, such as modesetting are updated, and out of tree drivers will
need equivalent, yet trivial, patch.
Note: we need to ensure that the screen private is unset and the screen
callbacks are restored in our CloseScreen function.
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
This might be an error or not, for example refusing to work on llvmpipe
is normal and expected. glamor_egl_init() will print X_ERROR messages if
appropriate, so we don't need to here.
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
The atomic driver has issues with modesetting when stealing
connectors from a different crtc, a black screen when doing rotation
on a different crtc, and in general is just a mapping of the legacy
helpers to atomic. This is already done in the kernel, so just
fallback to legacy by default until this is fixed.
Please backport to 1.20, as we don't want to enable it for everyone
there. It breaks for existing users.
The fixes to make the xserver more atomic have been pending on the
mailing list for ages.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110375
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110030
References: https://gitlab.freedesktop.org/xorg/xserver/merge_requests/36/commits
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>