2011-09-29 16:00:50 +01:00
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.\" shorthand for double quote that works everywhere.
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.ds q \N'34'
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2018-03-26 18:42:52 -04:00
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.TH MODESETTING @drivermansuffix@ @vendorversion@
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2011-09-29 16:00:50 +01:00
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.SH NAME
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modesetting \- video driver for framebuffer device
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.SH SYNOPSIS
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.nf
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.B "Section \*qDevice\*q"
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.BI " Identifier \*q" devname \*q
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.B " Driver \*qmodesetting\*q"
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.BI " BusID \*qpci:" bus : dev : func \*q
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\ \ ...
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.B EndSection
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.fi
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.SH DESCRIPTION
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.B modesetting
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2018-08-29 15:57:46 -04:00
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is an @xservername@ driver for KMS devices. This driver supports
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TrueColor visuals at framebuffer depths of 15, 16, 24, and 30. RandR
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1.2 is supported for multi-head configurations. Acceleration is available
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through glamor for devices supporting at least OpenGL ES 2.0 or OpenGL 2.1.
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If glamor is not enabled, a shadow framebuffer is configured based on the
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KMS drivers' preference (unless the framebuffer is 24 bits per pixel, in
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which case the shadow framebuffer is always used).
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2011-09-29 16:00:50 +01:00
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.SH SUPPORTED HARDWARE
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The
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.B modesetting
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driver supports all hardware where a KMS driver is available.
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modesetting uses the Linux DRM KMS ioctls and dumb object create/map.
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.SH CONFIGURATION DETAILS
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2025-03-29 13:36:54 -07:00
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Please refer to
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.BR @xconfigfile@ (@filemansuffix@)
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for general configuration details.
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This section only covers configuration details specific to this driver.
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2011-09-29 16:00:50 +01:00
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.PP
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For this driver it is not required to specify modes in the screen
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section of the config file. The
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.B modesetting
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driver can pick up the currently used video mode from the kernel
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driver and will use it if there are no video modes configured.
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.PP
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For PCI boards you might have to add a BusID line to the Device
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section. See above for a sample line.
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.PP
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The following driver
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.B Options
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are supported:
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.TP
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2015-08-05 00:08:40 +02:00
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.BI "Option \*qSWcursor\*q \*q" boolean \*q
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Selects software cursor. The default is
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.B off.
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.TP
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2011-09-29 16:00:50 +01:00
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.BI "Option \*qkmsdev\*q \*q" string \*q
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The framebuffer device to use. Default: /dev/dri/card0.
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.TP
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.BI "Option \*qShadowFB\*q \*q" boolean \*q
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Enable or disable use of the shadow framebuffer layer. Default: on.
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.TP
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2018-08-29 16:07:59 -04:00
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.BI "Option \*qDoubleShadow\*q \*q" boolean \*q
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Double-buffer shadow updates. When enabled, the driver will keep two copies of
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the shadow framebuffer. When the shadow framebuffer is flushed, the old and new
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versions of the shadow are compared, and only tiles that have actually changed
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are uploaded to the device. This is an optimization for server-class GPUs with
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a remote display function (typically VNC), where remote updates are triggered
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by any framebuffer write, so minimizing the amount of data uploaded is crucial.
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This defaults to enabled for ASPEED and Matrox G200 devices, and disabled
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otherwise.
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.TP
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2013-12-28 11:32:10 -08:00
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.BI "Option \*qAccelMethod\*q \*q" string \*q
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2018-08-29 15:57:46 -04:00
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One of \*qglamor\*q or \*qnone\*q. Default: glamor.
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2013-12-28 11:32:10 -08:00
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.TP
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2015-08-05 00:08:40 +02:00
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.BI "Option \*qPageFlip\*q \*q" boolean \*q
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Enable DRI3 page flipping. The default is
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.B on.
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.TP
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2021-10-01 08:49:10 +02:00
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.BI "Option \*qVariableRefresh\*q \*q" boolean \*q
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Enables support for enabling variable refresh on the Screen's CRTCs
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when an suitable application is flipping via the Present extension.
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.br
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The default is
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.B off.
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.TP
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modesetting: Add option for non-vsynced flips for "secondary" outputs.
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>
2021-08-30 05:42:04 +02:00
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.BI "Option \*qAsyncFlipSecondaries\*q \*q" boolean \*q
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Use async flips for secondary video outputs on multi-display setups. If a screen
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has multiple displays attached and DRI3 page flipping is used, then only one of
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the displays will have its page flip synchronized to vblank for tear-free
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presentation. This is the display that is used for presentation timing and
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timestamping, usually the one covering the biggest pixel area of the screen.
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All other displays ("Secondaries") will not synchronize their flips. This may
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cause some tearing on these displays, but it prevents a permanent or periodic
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slowdown or irritating judder of animations if not all video outputs are running
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synchronized with each other and with the same refresh rate. There is no perfect
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solution apart from perfectly synchronized outputs, but this option may give
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preferrable results if the displays in a multi-display setup mirror or clone
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each other. The default is
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.B off.
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.TP
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2015-07-22 03:56:13 +01:00
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.BI "Option \*qZaphodHeads\*q \*q" string \*q
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Specify the RandR output(s) to use with zaphod mode for a particular driver
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instance. If you use this option you must use this option for all instances
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of the driver.
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.br
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For example:
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.B
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Option \*qZaphodHeads\*q \*qLVDS,VGA-0\*q
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will assign xrandr outputs LVDS and VGA-0 to this instance of the driver.
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.TP
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2019-10-24 13:46:35 -07:00
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.BI "Option \*qUseGammaLUT\*q \*q" boolean \*q
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Enable or disable use of the GAMMA_LUT property, when available.
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When enabled, this option allows the driver to use gamma ramps with more
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2021-10-01 07:42:01 +02:00
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entries, if supported by the kernel. By default, GAMMA_LUT will be used for
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kms drivers which are known to be safe for use of GAMMA_LUT.
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2019-10-24 13:46:35 -07:00
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.TP
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2022-12-19 23:39:23 -08:00
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.BI "Option \*qTearFree\*q \*q" boolean \*q
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Enable tearing prevention using the hardware page flipping mechanism.
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It allocates two extra scanout buffers for each CRTC and utilizes damage
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tracking to minimize buffer copying and skip unnecessary flips when the
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screen's contents have not changed. It works on transformed screens too, such
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as rotated and scaled CRTCs. When PageFlip is enabled, fullscreen DRI
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applications will still have the discretion to not use tearing prevention.
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.br
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The default is
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2023-12-16 11:05:33 -08:00
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.B on.
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2022-12-19 23:39:23 -08:00
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.TP
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2022-12-15 16:57:01 +01:00
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.BI "Option \*qAtomic\*q \*q" boolean \*q
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Enable atomic modesetting when supported. The default is
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.B off.
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.TP
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2011-09-29 16:00:50 +01:00
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.SH "SEE ALSO"
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2025-03-29 13:36:54 -07:00
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.BR @xservername@ (@appmansuffix@),
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.BR @xconfigfile@ (@filemansuffix@),
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.BR Xserver (@appmansuffix@),
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.BR X (@miscmansuffix@)
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2011-09-29 16:00:50 +01:00
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.SH AUTHORS
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Authors include: Dave Airlie
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