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drm: apple: Adaptive Sync/ProMotion#477

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chadmed wants to merge 7 commits into
AsahiLinux:asahi-wipfrom
chadmed:dcp/vrr
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drm: apple: Adaptive Sync/ProMotion#477
chadmed wants to merge 7 commits into
AsahiLinux:asahi-wipfrom
chadmed:dcp/vrr

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@chadmed chadmed commented Apr 5, 2026

Tested:

  • Adaptive Sync over DisplayPort (Dell S2721DGF, [48, 165] Hz)
  • Apple ProMotion on 14" and 16" MacBook Pros (tested [24, 120] Hz)

Not tested:

  • Adaptive Sync over HDMI (I have no HDMI 2.x displays)

What works:

  • "Modesetting" in and out of Adaptive Sync
  • mpv... mostly
  • Games running via Proton via Steam via FEX via muvm
  • Native AArch64 games
  • Forcing Adaptive Sync on and sitting at the desktop at minimum refresh rate

What doesn't

  • Firefox will always render at the display's refresh rate
  • On the internal MBP displays only, mpv's gpu and gpu-next outputs leak file descriptors and halt the GPU when in fullscreen. Other backends work fine, other applications work fine, gpu and gpu-next work fine when not in fullscreen...

What needs work

  • The VRR timestamps are best guesses only. We know they are always within a few frames of each other, meaning that they are likely something to do with swap submission and presentation time, but what exactly remains unclear.
  • Wrapping set_digital_out_mode in a dcpep callback seems kind of silly? There's probably a smarter way to do this.

jannau
jannau requested changes Apr 5, 2026
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How did you verify this does anything at all on MacBook Pro internal displays? I would expect that this does nothing without EDID with adaptive sync data.

Comment thread drivers/gpu/drm/apple/parser.c
Comment thread drivers/gpu/drm/apple/parser.h Outdated
Comment thread drivers/gpu/drm/apple/iomfb_template.h Outdated
Comment thread drivers/gpu/drm/apple/iomfb_template.c Outdated
Comment thread drivers/gpu/drm/apple/iomfb_template.c Outdated
Comment thread drivers/gpu/drm/apple/iomfb_template.c Outdated
Comment thread drivers/gpu/drm/apple/iomfb_template.c Outdated
Comment thread drivers/gpu/drm/apple/iomfb_template.c Outdated
Comment thread drivers/gpu/drm/apple/iomfb_template.c Outdated
Comment thread drivers/gpu/drm/apple/iomfb_template.c Outdated
@chadmed chadmed force-pushed the dcp/vrr branch 2 times, most recently from 585c039 to ae20e32 Compare April 6, 2026 06:22
jannau
jannau reviewed Apr 6, 2026
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Comment thread drivers/gpu/drm/apple/iomfb_template.c Outdated
Comment thread drivers/gpu/drm/apple/iomfb_template.c Outdated
Comment thread drivers/gpu/drm/apple/iomfb_template.c
Comment thread drivers/gpu/drm/apple/iomfb_template.c Outdated
@chadmed chadmed force-pushed the dcp/vrr branch 2 times, most recently from 2e41bc2 to 31bf70d Compare April 7, 2026 12:14
jannau
jannau reviewed Apr 12, 2026
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Comment thread drivers/gpu/drm/apple/dcp.c Outdated
Comment thread drivers/gpu/drm/apple/iomfb_template.c Outdated
Comment thread drivers/gpu/drm/apple/dcp.c Outdated
Comment thread drivers/gpu/drm/apple/dcp.c Outdated
Comment thread drivers/gpu/drm/apple/iomfb_template.c Outdated
Comment thread drivers/gpu/drm/apple/parser.h Outdated
@jannau jannau force-pushed the asahi-wip branch 2 times, most recently from 1c56451 to ee6177c Compare May 18, 2026 19:11
chadmed added 7 commits June 7, 2026 14:50
@chadmed
drm: apple: Do not set IOMFBParameter_adaptive_sync on poweron
23682c5 
This was actually unnecessary, and having dcp_on_set_parameter as
a dcp_callback_t will introduce some complicated duplication when
enabling VRR. Remove this callback and just set the display handle
on poweron instead.

Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
@chadmed
drm: apple: Add preliminary VRR support
459e049 
DCP supports VRR/Adaptive Sync, with its enormous firmware blob
handling the low-level details for us. Display refresh rate is
determined by the swap timing values provided to DCP on each
swap request.

VRR is activated by setting IOMFBadaptive_sync_parameter::minRR
and then requesting a modeset.

Wire up all of the required KMS properties to expose VRR to
userspace, and tell DCP to enable it when supported. This
enables VRR *unconditionally* for supported sinks, which will
be fixed in a future commit.

Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
@chadmed
drm: apple: Force modeset when VRR is toggled
11741c8 
DCP requires a "modeset" to trigger the upload of the SDP
to the display. On some monitors, this is instant. On others,
this seems to take as long as a real modeset. Given that in
either case we still blank the display, let's just force a
full modeset when VRR is toggled on or off.

Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
@chadmed
drm: apple: Set swap timestamps to sane values for Adaptive Sync
67e5ae5 
Setting these timestamps to a dummy value worked fine for enabling
a fixed 120 Hz mode on the MacBook Pros, however doing so causes
Adaptive Sync displays to simply switch between full and minimum
refresh rates. Setting these timestamps based on the swap pacing
seems to fix this, and makes the display's refresh rate match
the incoming swap rate.

Note that the names and values are best-guess only. These seem
to work fine for driving VRR displays, but may still be incorrect.

Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
@chadmed
drm: apple: Set min and max VRRs for MacBook Pros
50830fc 
Since these machines do not have proper EDID/DisplayID data, we need
to help the driver along a little bit. We know that "ProMotion" displays
can do 24-120 Hz VRR, so let's populate the mode with those values.

Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
@chadmed
drm: apple: Only use swap timestamps if VRR is actually active
8836a0f 
macOS is inconsistent with how it uses DCP timestamps. Some swaps
don't use them at all. We know they are required for VRR display
modes to work properly, so let's just turn them on when we are
connected to a VRR display. This includes the 120 Hz mode on
the 14" and 16" MacBook Pros.

Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
@chadmed
NOUPSTREAM: drm: apple: Hide VRR behind a module parameter
8a80800 
Given that DCP requires a modeset to activate VRR, and given that
this is explicitly banned by KMS API contract and VESA DisplayPort
specification, hide this experimental support behind a module param.

Interestingly, the HDMI spec does not require a modeset-free VRR
transition. For this reason, it is expected that the KMS API contract
may change in the future, as both Intel and AMD hardware require
a modeset to enable VRR in some circumstances. Either VRR will be
expected to be enabled whenever it is supported, *or* modesetting
to toggle it on or off will be allowed. When that happens, this
commit *must* be reverted.

Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
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