From db6c10696d5f83c0534fdcc16e91333befb8542d Mon Sep 17 00:00:00 2001
From: James Calligeros <jcalligeros99@gmail.com>
Date: Mon, 6 Apr 2026 10:25:39 +1000
Subject: [PATCH 1/8] drm: apple: Define IOMFB parameter for Adaptive Sync

IOMFB exposes a method that allows firmware consumers to change
display behaviour parameters at runtime. One such parameter is
IOMFBParameter_adaptive_sync, which allows DCP to be informed
of the desired minimum refresh rate, media target rate, and
fractional rate.

Add an enum to define the supported parameters, and add
IOMFBPARAM_ADAPTIVE_SYNC to it as a starting point.

Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
---
 drivers/gpu/drm/apple/iomfb.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/apple/iomfb.h b/drivers/gpu/drm/apple/iomfb.h
index 5799586106713e..8a871db0b94a70 100644
--- a/drivers/gpu/drm/apple/iomfb.h
+++ b/drivers/gpu/drm/apple/iomfb.h
@@ -46,6 +46,15 @@ enum dcpep_type {
 	IOMFB_MESSAGE_TYPE_MSG = 2,
 };
 
+/*
+ * IOMFB supports the setting of a number of parameters
+ * that alter various aspects of the connected sink's
+ * behaviour at runtime.
+ */
+enum iomfb_parameter {
+	IOMFBPARAM_ADAPTIVE_SYNC = 14,
+};
+
 #define IOMFB_MESSAGE_TYPE	GENMASK_ULL( 3,  0)
 
 /* Message */

From 9e24a0153576e201eee5bc2ca84a5226e1fb6e31 Mon Sep 17 00:00:00 2001
From: James Calligeros <jcalligeros99@gmail.com>
Date: Mon, 6 Apr 2026 10:21:44 +1000
Subject: [PATCH 2/8] drm: apple: Do not set IOMFBParameter_adaptive_sync on
 poweron

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>
---
 drivers/gpu/drm/apple/iomfb_template.c | 29 +++++---------------------
 1 file changed, 5 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/apple/iomfb_template.c b/drivers/gpu/drm/apple/iomfb_template.c
index 1b7ecbcba925d1..82a5fce70bd442 100644
--- a/drivers/gpu/drm/apple/iomfb_template.c
+++ b/drivers/gpu/drm/apple/iomfb_template.c
@@ -784,21 +784,6 @@ static void dcp_on_set_power_state(struct apple_dcp *dcp, void *out, void *cooki
 	dcp_set_power_state(dcp, false, &req, dcp_on_final, cookie);
 }
 
-static void dcp_on_set_parameter(struct apple_dcp *dcp, void *out, void *cookie)
-{
-	struct dcp_set_parameter_dcp param = {
-		.param = 14,
-		.value = { 0 },
-#if DCP_FW_VER >= DCP_FW_VERSION(13, 2, 0)
-		.count = 3,
-#else
-		.count = 1,
-#endif
-	};
-
-	dcp_set_parameter_dcp(dcp, false, &param, dcp_on_set_power_state, cookie);
-}
-
 void DCP_FW_NAME(iomfb_poweron)(struct apple_dcp *dcp)
 {
 	struct dcp_wait_cookie *cookie;
@@ -815,15 +800,11 @@ void DCP_FW_NAME(iomfb_poweron)(struct apple_dcp *dcp)
 	/* increase refcount to ensure the receiver has a reference */
 	kref_get(&cookie->refcount);
 
-	if (dcp->main_display) {
-		handle = 0;
-		dcp_set_display_device(dcp, false, &handle, dcp_on_set_power_state,
-				       cookie);
-	} else {
-		handle = 2;
-		dcp_set_display_device(dcp, false, &handle,
-				       dcp_on_set_parameter, cookie);
-	}
+	handle = dcp->main_display ? 0 : 2;
+
+	dcp_set_display_device(dcp, false, &handle, dcp_on_set_power_state,
+			       cookie);
+
 	ret = wait_for_completion_timeout(&cookie->done, msecs_to_jiffies(10000));
 
 	if (ret == 0) {

From b7a63573a87dd7e37b6b1a747515429e021dfaf4 Mon Sep 17 00:00:00 2001
From: James Calligeros <jcalligeros99@gmail.com>
Date: Fri, 3 Apr 2026 20:31:17 +1000
Subject: [PATCH 3/8] drm: apple: Add preliminary VRR support

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>
---
 drivers/gpu/drm/apple/apple_drv.c      |  4 +++
 drivers/gpu/drm/apple/iomfb.c          |  1 +
 drivers/gpu/drm/apple/iomfb_template.c | 46 ++++++++++++++++++++++++--
 drivers/gpu/drm/apple/parser.c         | 32 ++++++++++++++++--
 drivers/gpu/drm/apple/parser.h         |  2 ++
 5 files changed, 79 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/apple/apple_drv.c b/drivers/gpu/drm/apple/apple_drv.c
index 0f36dad6f96351..31b86e909014ad 100644
--- a/drivers/gpu/drm/apple/apple_drv.c
+++ b/drivers/gpu/drm/apple/apple_drv.c
@@ -335,6 +335,10 @@ static int apple_probe_per_dcp(struct device *dev,
 	if (ret)
 		return ret;
 
+	ret = drm_connector_attach_vrr_capable_property(&connector->base);
+	if (ret)
+		return ret;
+
 	connector->base.polled = DRM_CONNECTOR_POLL_HPD;
 	connector->connected = false;
 	connector->dcp = dcp;
diff --git a/drivers/gpu/drm/apple/iomfb.c b/drivers/gpu/drm/apple/iomfb.c
index 1d9448f0f4dc47..1d90e4a2597303 100644
--- a/drivers/gpu/drm/apple/iomfb.c
+++ b/drivers/gpu/drm/apple/iomfb.c
@@ -244,6 +244,7 @@ void dcp_hotplug(struct work_struct *work)
 
 	if (!connector->connected) {
 		drm_edid_free(connector->drm_edid);
+		drm_connector_set_vrr_capable_property(&connector->base, false);
 		connector->drm_edid = NULL;
 	}
 
diff --git a/drivers/gpu/drm/apple/iomfb_template.c b/drivers/gpu/drm/apple/iomfb_template.c
index 82a5fce70bd442..e090797743831f 100644
--- a/drivers/gpu/drm/apple/iomfb_template.c
+++ b/drivers/gpu/drm/apple/iomfb_template.c
@@ -546,8 +546,9 @@ static u8 dcpep_cb_prop_chunk(struct apple_dcp *dcp,
 static bool dcpep_process_chunks(struct apple_dcp *dcp,
 				 struct dcp_set_dcpav_prop_end_req *req)
 {
+	struct apple_connector *connector = dcp->connector;
 	struct dcp_parse_ctx ctx;
-	int ret;
+	int ret, i;
 
 	if (!dcp->chunks.data) {
 		dev_warn(dcp->dev, "ignoring spurious end\n");
@@ -589,6 +590,15 @@ static bool dcpep_process_chunks(struct apple_dcp *dcp,
 		dcp_set_dimensions(dcp);
 	}
 
+	if (connector) {
+		for (i = 0; i < dcp->nr_modes; i++) {
+			if (dcp->modes[i].vrr) {
+				drm_connector_set_vrr_capable_property(&connector->base, true);
+				break;
+			}
+		}
+	}
+
 	return true;
 }
 
@@ -1171,6 +1181,33 @@ static void complete_set_digital_out_mode(struct apple_dcp *dcp, void *data,
 	}
 }
 
+/* Changes to Adaptive Sync require a trip through set_digital_out_mode */
+static void dcp_on_set_adaptive_sync(struct apple_dcp *dcp, void *out, void *cookie)
+{
+	dcp_set_digital_out_mode(dcp, false, &dcp->mode,
+				 complete_set_digital_out_mode, cookie);
+}
+
+static void dcp_set_adaptive_sync(struct apple_dcp *dcp, u32 rate, void *cookie)
+{
+	struct dcp_set_parameter_dcp param = {
+		.param = IOMFBPARAM_ADAPTIVE_SYNC,
+		.value = {
+			rate,              /* minRR */
+			0,                 /* mediaTargetRate */
+			0,                 /* Fractional Rate (?) */
+			0,                 /* unused */
+		},
+#if DCP_FW_VER >= DCP_FW_VERSION(13, 2, 0)
+		.count = 3,
+#else
+		.count = 1,
+#endif
+	};
+
+	dcp_set_parameter_dcp(dcp, false, &param, dcp_on_set_adaptive_sync, cookie);
+}
+
 int DCP_FW_NAME(iomfb_modeset)(struct apple_dcp *dcp,
 			       struct drm_crtc_state *crtc_state)
 {
@@ -1225,8 +1262,11 @@ int DCP_FW_NAME(iomfb_modeset)(struct apple_dcp *dcp,
 
 	dcp->during_modeset = true;
 
-	dcp_set_digital_out_mode(dcp, false, &dcp->mode,
-				 complete_set_digital_out_mode, cookie);
+	if (mode->vrr)
+		dcp_set_adaptive_sync(dcp, mode->min_vrr, cookie);
+	else
+		dcp_set_digital_out_mode(dcp, false, &dcp->mode,
+					 complete_set_digital_out_mode, cookie);
 
 	/*
 	 * The DCP firmware has an internal timeout of ~8 seconds for
diff --git a/drivers/gpu/drm/apple/parser.c b/drivers/gpu/drm/apple/parser.c
index 7c7af18a7c7e15..85c303fa04649b 100644
--- a/drivers/gpu/drm/apple/parser.c
+++ b/drivers/gpu/drm/apple/parser.c
@@ -194,6 +194,26 @@ static int parse_int(struct dcp_parse_ctx *handle, s64 *value)
 	return 0;
 }
 
+/*
+ * DCP stores VRR refresh rates in 64-bit regions, however the number is actually an
+ * unsigned Q16.16 with the high 32 bits unused.
+ */
+static int parse_q1616(struct dcp_parse_ctx *handle, u32 *value)
+{
+	s64 dcp_int;
+	u32 in;
+	int ret;
+
+	ret = parse_int(handle, &dcp_int);
+	if (ret)
+		return ret;
+
+	in = dcp_int & 0xffffffff;
+
+	memcpy(value, &in, sizeof(*value));
+	return 0;
+}
+
 static int parse_bool(struct dcp_parse_ctx *handle, bool *b)
 {
 	const struct dcp_parse_tag *tag = parse_tag_of_type(handle, DCP_TYPE_BOOL);
@@ -454,6 +474,10 @@ static int parse_mode(struct dcp_parse_ctx *handle,
 			ret = parse_dimension(it.handle, &horiz);
 		else if (!strcmp(key, "VerticalAttributes"))
 			ret = parse_dimension(it.handle, &vert);
+		else if (!strcmp(key, "MinimumVariableRefreshRate"))
+			ret = parse_q1616(it.handle, &out->min_vrr);
+		else if (!strcmp(key, "MaximumVariableRefreshRate"))
+			ret = parse_q1616(it.handle, &out->max_vrr);
 		else if (!strcmp(key, "ColorModes"))
 			ret = parse_color_modes(it.handle, out);
 		else if (!strcmp(key, "ID"))
@@ -502,15 +526,17 @@ static int parse_mode(struct dcp_parse_ctx *handle,
 	/*
 	* HACK:
 	* Mark the 120 Hz mode on j314/j316 (identified by resolution) as vrr.
-	* We still do not know how to drive VRR but at least seetinng timestamps
-	* in the the swap_surface message to non-zero values drives the display
-	* at 120 fps.
+	* Setting timestamps in the the swap_surface message to non-zero
+	* values drives the display at 120 fps.
 	*/
 	if (vert.precise_sync_rate >> 16 == 120 &&
 	    ((horiz.active == 3024 && vert.active == 1964) ||
 	     (horiz.active == 3456 && vert.active == 2234)))
 		out->vrr = true;
 
+	if (out->min_vrr && out->max_vrr)
+		out->vrr = true;
+
 	vert.active -= notch_height;
 	vert.sync_width += notch_height;
 
diff --git a/drivers/gpu/drm/apple/parser.h b/drivers/gpu/drm/apple/parser.h
index e03ee06ae98a75..a7af17bfe35d36 100644
--- a/drivers/gpu/drm/apple/parser.h
+++ b/drivers/gpu/drm/apple/parser.h
@@ -92,6 +92,8 @@ struct dcp_display_mode {
 	struct dcp_color_mode sdr;
 	struct dcp_color_mode best;
 	bool vrr;
+	u32 min_vrr;
+	u32 max_vrr;
 };
 
 struct dimension {

From 02335536967ff38944067189bf58ed57467ba6fa Mon Sep 17 00:00:00 2001
From: James Calligeros <jcalligeros99@gmail.com>
Date: Sat, 4 Apr 2026 17:43:49 +1000
Subject: [PATCH 4/8] drm: apple: Force modeset when VRR is toggled

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>
---
 drivers/gpu/drm/apple/dcp-internal.h   | 1 +
 drivers/gpu/drm/apple/dcp.c            | 4 ++++
 drivers/gpu/drm/apple/iomfb_template.c | 3 ++-
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/apple/dcp-internal.h b/drivers/gpu/drm/apple/dcp-internal.h
index f2eb2483c9a880..0a6859448e19eb 100644
--- a/drivers/gpu/drm/apple/dcp-internal.h
+++ b/drivers/gpu/drm/apple/dcp-internal.h
@@ -186,6 +186,7 @@ struct apple_dcp {
 	bool during_modeset;
 	bool valid_mode;
 	bool use_timestamps;
+	bool vrr_enabled;
 	struct dcp_set_digital_out_mode_req mode;
 
 	/* completion for active turning true */
diff --git a/drivers/gpu/drm/apple/dcp.c b/drivers/gpu/drm/apple/dcp.c
index 9dfc3fd002f530..dc69d1a9ef7f7e 100644
--- a/drivers/gpu/drm/apple/dcp.c
+++ b/drivers/gpu/drm/apple/dcp.c
@@ -361,6 +361,10 @@ int dcp_crtc_atomic_check(struct drm_crtc *crtc, struct drm_atomic_state *state)
 		return -EINVAL;
 	}
 
+	if (dcp->vrr_enabled != crtc_state->vrr_enabled) {
+		crtc_state->mode_changed = true;
+	}
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/apple/iomfb_template.c b/drivers/gpu/drm/apple/iomfb_template.c
index e090797743831f..fa998dcf5ce4f1 100644
--- a/drivers/gpu/drm/apple/iomfb_template.c
+++ b/drivers/gpu/drm/apple/iomfb_template.c
@@ -1263,7 +1263,7 @@ int DCP_FW_NAME(iomfb_modeset)(struct apple_dcp *dcp,
 	dcp->during_modeset = true;
 
 	if (mode->vrr)
-		dcp_set_adaptive_sync(dcp, mode->min_vrr, cookie);
+		dcp_set_adaptive_sync(dcp, crtc_state->vrr_enabled ? mode->min_vrr : 0, cookie);
 	else
 		dcp_set_digital_out_mode(dcp, false, &dcp->mode,
 					 complete_set_digital_out_mode, cookie);
@@ -1294,6 +1294,7 @@ int DCP_FW_NAME(iomfb_modeset)(struct apple_dcp *dcp,
 			jiffies_to_msecs(ret));
 	}
 	dcp->valid_mode = true;
+	dcp->vrr_enabled = crtc_state->vrr_enabled;
 
 	return 0;
 }

From 8c9cd61cc6765bffc89de7e33be86edbf20acdf6 Mon Sep 17 00:00:00 2001
From: James Calligeros <jcalligeros99@gmail.com>
Date: Fri, 3 Apr 2026 21:59:47 +1000
Subject: [PATCH 5/8] drm: apple: Set swap timestamps to sane values for
 Adaptive Sync

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>
---
 drivers/gpu/drm/apple/iomfb_template.c | 21 ++++++++++++++++-----
 drivers/gpu/drm/apple/iomfb_template.h |  6 +++---
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/apple/iomfb_template.c b/drivers/gpu/drm/apple/iomfb_template.c
index fa998dcf5ce4f1..d37b7c77e73241 100644
--- a/drivers/gpu/drm/apple/iomfb_template.c
+++ b/drivers/gpu/drm/apple/iomfb_template.c
@@ -1299,6 +1299,15 @@ int DCP_FW_NAME(iomfb_modeset)(struct apple_dcp *dcp,
 	return 0;
 }
 
+/*
+ * DCP timestamps are expressed in system timer ticks. Approximate
+ * this by converting from ktime nanoseconds to 24 MHz ticks.
+ */
+static u64 ns_to_mach(u64 ns)
+{
+	return ns * 3 / 125;
+}
+
 void DCP_FW_NAME(iomfb_flush)(struct apple_dcp *dcp, struct drm_crtc *crtc, struct drm_atomic_state *state)
 {
 	struct drm_plane *plane;
@@ -1415,12 +1424,14 @@ void DCP_FW_NAME(iomfb_flush)(struct apple_dcp *dcp, struct drm_crtc *crtc, stru
 
 	if (has_surface && dcp->use_timestamps) {
 		/*
-		 * Fake timstamps to get 120hz refresh rate. It looks
-		 * like the actual value does not matter, as long  as it is non zero.
+		 * TODO: ascertain with certainty what these timestamps
+		 * are. They are something to do with presentation timing,
+		 * but that is all we know for sure. These values seem to
+		 * work well with VRR.
 		 */
-		req->swap.ts1 = 120;
-		req->swap.ts2 = 120;
-		req->swap.ts3 = 120;
+		req->swap.unk_pres_ts1 = ns_to_mach(ktime_get_ns());
+		req->swap.unk_pres_ts2 = ns_to_mach(ktime_to_ns(dcp->swap_start));
+		req->swap.unk_pres_ts3 = req->swap.unk_pres_ts1;
 	}
 
 	/* These fields should be set together */
diff --git a/drivers/gpu/drm/apple/iomfb_template.h b/drivers/gpu/drm/apple/iomfb_template.h
index 8efab49cc53d08..e74672da712efa 100644
--- a/drivers/gpu/drm/apple/iomfb_template.h
+++ b/drivers/gpu/drm/apple/iomfb_template.h
@@ -18,14 +18,14 @@
 #include "version_utils.h"
 
 struct DCP_FW_NAME(dcp_swap) {
-	u64 ts1;
-	u64 ts2;
+	u64 unk_pres_ts1;
+	u64 unk_pres_ts2;
 
 	u64 unk_10;
 	u64 unk_18;
 	u64 ts64_unk;
 	u64 unk_28;
-	u64 ts3;
+	u64 unk_pres_ts3;
 	u64 unk_38;
 
 	u64 flags1;

From f1ed883a55e1c8deda7b99941824b7a68e492933 Mon Sep 17 00:00:00 2001
From: James Calligeros <jcalligeros99@gmail.com>
Date: Sat, 4 Apr 2026 23:32:06 +1000
Subject: [PATCH 6/8] drm: apple: Set min and max VRRs for MacBook Pros

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>
---
 drivers/gpu/drm/apple/parser.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/apple/parser.c b/drivers/gpu/drm/apple/parser.c
index 85c303fa04649b..dd1d76936fb18b 100644
--- a/drivers/gpu/drm/apple/parser.c
+++ b/drivers/gpu/drm/apple/parser.c
@@ -531,8 +531,11 @@ static int parse_mode(struct dcp_parse_ctx *handle,
 	*/
 	if (vert.precise_sync_rate >> 16 == 120 &&
 	    ((horiz.active == 3024 && vert.active == 1964) ||
-	     (horiz.active == 3456 && vert.active == 2234)))
+	     (horiz.active == 3456 && vert.active == 2234))) {
+		out->min_vrr = 24 << 16;
+		out->max_vrr = 120 << 16;
 		out->vrr = true;
+	}
 
 	if (out->min_vrr && out->max_vrr)
 		out->vrr = true;

From 7d6080cb13544280085bf28f6a43d4226ae9ad80 Mon Sep 17 00:00:00 2001
From: James Calligeros <jcalligeros99@gmail.com>
Date: Sun, 5 Apr 2026 13:08:29 +1000
Subject: [PATCH 7/8] drm: apple: Only use swap timestamps if VRR is actually
 active

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>
---
 drivers/gpu/drm/apple/iomfb_template.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/apple/iomfb_template.c b/drivers/gpu/drm/apple/iomfb_template.c
index d37b7c77e73241..2390be534dfdfd 100644
--- a/drivers/gpu/drm/apple/iomfb_template.c
+++ b/drivers/gpu/drm/apple/iomfb_template.c
@@ -1247,8 +1247,8 @@ int DCP_FW_NAME(iomfb_modeset)(struct apple_dcp *dcp,
 		.timing_mode_id = mode->timing_mode_id
 	};
 
-	/* Keep track of suspected vrr modes */
-	dcp->use_timestamps = mode->vrr;
+	/* Use DCP swap timestamps on MacBook Pros with VRR */
+	dcp->use_timestamps = mode->vrr && dcp->main_display;
 
 	cookie = kzalloc(sizeof(*cookie), GFP_KERNEL);
 	if (!cookie) {
@@ -1422,7 +1422,7 @@ void DCP_FW_NAME(iomfb_flush)(struct apple_dcp *dcp, struct drm_crtc *crtc, stru
 		req->clear = 1;
 	}
 
-	if (has_surface && dcp->use_timestamps) {
+	if (has_surface && (dcp->use_timestamps || crtc_state->vrr_enabled)) {
 		/*
 		 * TODO: ascertain with certainty what these timestamps
 		 * are. They are something to do with presentation timing,

From bf1298c03878e306134f94f9eb54fa3017b7bbd5 Mon Sep 17 00:00:00 2001
From: James Calligeros <jcalligeros99@gmail.com>
Date: Tue, 7 Apr 2026 21:43:32 +1000
Subject: [PATCH 8/8] NOUPSTREAM: drm: apple: Hide VRR behind a module
 parameter

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>
---
 drivers/gpu/drm/apple/dcp.c            | 10 +++++---
 drivers/gpu/drm/apple/iomfb_template.c | 33 ++++++++++++++------------
 2 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/apple/dcp.c b/drivers/gpu/drm/apple/dcp.c
index dc69d1a9ef7f7e..83ba20f7f02568 100644
--- a/drivers/gpu/drm/apple/dcp.c
+++ b/drivers/gpu/drm/apple/dcp.c
@@ -58,6 +58,10 @@ static bool unstable_edid = true;
 module_param(unstable_edid, bool, 0644);
 MODULE_PARM_DESC(unstable_edid, "Enable unstable EDID retrival support");
 
+bool force_vrr;
+module_param(force_vrr, bool, 0644);
+MODULE_PARM_DESC(force_vrr, "Always enable Adaptive Sync/ProMotion on supported displays");
+
 /* copied and simplified from drm_vblank.c */
 static void send_vblank_event(struct drm_device *dev,
 		struct drm_pending_vblank_event *e,
@@ -361,9 +365,9 @@ int dcp_crtc_atomic_check(struct drm_crtc *crtc, struct drm_atomic_state *state)
 		return -EINVAL;
 	}
 
-	if (dcp->vrr_enabled != crtc_state->vrr_enabled) {
-		crtc_state->mode_changed = true;
-	}
+	// if (dcp->vrr_enabled != crtc_state->vrr_enabled) {
+	// 	crtc_state->mode_changed = true;
+	// }
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/apple/iomfb_template.c b/drivers/gpu/drm/apple/iomfb_template.c
index 2390be534dfdfd..0e5d5908a3c9b6 100644
--- a/drivers/gpu/drm/apple/iomfb_template.c
+++ b/drivers/gpu/drm/apple/iomfb_template.c
@@ -34,6 +34,8 @@
 /* Register defines used in bandwidth setup structure */
 #define REG_DOORBELL_BIT(idx) (2 + (idx))
 
+extern bool force_vrr;
+
 struct dcp_wait_cookie {
 	struct kref refcount;
 	struct completion done;
@@ -546,9 +548,9 @@ static u8 dcpep_cb_prop_chunk(struct apple_dcp *dcp,
 static bool dcpep_process_chunks(struct apple_dcp *dcp,
 				 struct dcp_set_dcpav_prop_end_req *req)
 {
-	struct apple_connector *connector = dcp->connector;
+	// struct apple_connector *connector = dcp->connector;
 	struct dcp_parse_ctx ctx;
-	int ret, i;
+	int ret; //, i;
 
 	if (!dcp->chunks.data) {
 		dev_warn(dcp->dev, "ignoring spurious end\n");
@@ -590,14 +592,14 @@ static bool dcpep_process_chunks(struct apple_dcp *dcp,
 		dcp_set_dimensions(dcp);
 	}
 
-	if (connector) {
-		for (i = 0; i < dcp->nr_modes; i++) {
-			if (dcp->modes[i].vrr) {
-				drm_connector_set_vrr_capable_property(&connector->base, true);
-				break;
-			}
-		}
-	}
+	// if (connector) {
+	// 	for (i = 0; i < dcp->nr_modes; i++) {
+	// 		if (dcp->modes[i].vrr) {
+	// 			drm_connector_set_vrr_capable_property(&connector->base, true);
+	// 			break;
+	// 		}
+	// 	}
+	// }
 
 	return true;
 }
@@ -1262,11 +1264,12 @@ int DCP_FW_NAME(iomfb_modeset)(struct apple_dcp *dcp,
 
 	dcp->during_modeset = true;
 
-	if (mode->vrr)
-		dcp_set_adaptive_sync(dcp, crtc_state->vrr_enabled ? mode->min_vrr : 0, cookie);
-	else
+	if (mode->vrr) {
+		dcp_set_adaptive_sync(dcp, force_vrr ? mode->min_vrr : 0, cookie);
+	} else {
 		dcp_set_digital_out_mode(dcp, false, &dcp->mode,
 					 complete_set_digital_out_mode, cookie);
+	}
 
 	/*
 	 * The DCP firmware has an internal timeout of ~8 seconds for
@@ -1294,7 +1297,7 @@ int DCP_FW_NAME(iomfb_modeset)(struct apple_dcp *dcp,
 			jiffies_to_msecs(ret));
 	}
 	dcp->valid_mode = true;
-	dcp->vrr_enabled = crtc_state->vrr_enabled;
+	dcp->vrr_enabled = mode->vrr && force_vrr;
 
 	return 0;
 }
@@ -1422,7 +1425,7 @@ void DCP_FW_NAME(iomfb_flush)(struct apple_dcp *dcp, struct drm_crtc *crtc, stru
 		req->clear = 1;
 	}
 
-	if (has_surface && (dcp->use_timestamps || crtc_state->vrr_enabled)) {
+	if (has_surface && (dcp->use_timestamps || crtc_state->vrr_enabled || force_vrr)) {
 		/*
 		 * TODO: ascertain with certainty what these timestamps
 		 * are. They are something to do with presentation timing,