drm: apple: Adaptive Sync/ProMotion

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;

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 */

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,
@@ -361,6 +365,10 @@ 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;
 }
 

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;
 	}
 

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 */

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;
@@ -546,8 +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 dcp_parse_ctx ctx;
-	int ret;
+	int ret; //, i;
 
 	if (!dcp->chunks.data) {
 		dev_warn(dcp->dev, "ignoring spurious end\n");
@@ -589,6 +592,15 @@ 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;
 }
 
@@ -784,21 +796,6 @@ 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 +812,11 @@ 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) {
@@ -1190,6 +1183,33 @@ 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)
 {
@@ -1229,8 +1249,8 @@ 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) {
@@ -1244,8 +1264,12 @@ 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, 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
@@ -1273,10 +1297,20 @@ int DCP_FW_NAME(iomfb_modeset)(struct apple_dcp *dcp,
 			jiffies_to_msecs(ret));
 	}
 	dcp->valid_mode = true;
+	dcp->vrr_enabled = mode->vrr && force_vrr;
 
 	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;
@@ -1391,14 +1425,16 @@ 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 || force_vrr)) {
 		/*
-		 * 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 */

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;

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"))
@@ -502,13 +526,18 @@ 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)))
+	     (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;
 
 	vert.active -= notch_height;

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 {