drm: apple: set timestamps for 120hz

The dcp does not seem to care much about the values in ts1, ts2 and ts3, as long
as they are non zero. This commit fills the timestamp with a dummy value
of 120 if a refresh-rate of 120hz is selected.
This is enough to get a refresh rate of 120hz.

MacOS also sets flags1 and flags2. I have no idea what exactly those values
indicate, but I did do not need to set any of them to get 120hz.

Signed-off-by: Oliver Bestmann <oliver.bestmann@googlemail.com>

Signed-off-by: Janne Grunau <j@jannau.net>

Author: oliverbestmann

drivers/gpu/drm/apple/dcp-internal.h

@@ -184,6 +184,7 @@ struct apple_dcp {
 	/* Current display mode */
 	bool during_modeset;
 	bool valid_mode;
+	bool use_timestamps;
 	struct dcp_set_digital_out_mode_req mode;
 
 	/* completion for active turning true */

drivers/gpu/drm/apple/iomfb_template.c

@@ -1210,15 +1210,18 @@ int DCP_FW_NAME(iomfb_modeset)(struct apple_dcp *dcp,
 	if (cmode)
 		dev_info(dcp->dev,
 			"set_digital_out_mode() color mode depth:%hhu format:%u "
-			"colorimetry:%u eotf:%u range:%u\n", cmode->depth,
+			"colorimetry:%u eotf:%u range:%u vrr:%u\n", cmode->depth,
 			cmode->format, cmode->colorimetry, cmode->eotf,
-			cmode->range);
+			cmode->range, mode->vrr);
 
 	dcp->mode = (struct dcp_set_digital_out_mode_req){
 		.color_mode_id = mode->color_mode_id,
 		.timing_mode_id = mode->timing_mode_id
 	};
 
+	/* Keep track of suspected vrr modes */
+	dcp->use_timestamps = mode->vrr;
+
 	cookie = kzalloc(sizeof(*cookie), GFP_KERNEL);
 	if (!cookie) {
 		return -ENOMEM;
@@ -1408,6 +1411,16 @@ void DCP_FW_NAME(iomfb_flush)(struct apple_dcp *dcp, struct drm_crtc *crtc, stru
 		req->clear = 1;
 	}
 
+	if (has_surface && dcp->use_timestamps) {
+		/*
+		 * Fake timstamps to get 120hz refresh rate. It looks
+		 * like the actual value does not matter, as long  as it is non zero.
+		 */
+		req->swap.ts1 = 120;
+		req->swap.ts2 = 120;
+		req->swap.ts3 = 120;
+	}
+
 	/* These fields should be set together */
 	req->swap.swap_completed = req->swap.swap_enabled;
 

drivers/gpu/drm/apple/iomfb_template.h

@@ -18,7 +18,14 @@
 struct DCP_FW_NAME(dcp_swap) {
 	u64 ts1;
 	u64 ts2;
-	u64 unk_10[6];
+
+	u64 unk_10;
+	u64 unk_18;
+	u64 ts64_unk;
+	u64 unk_28;
+	u64 ts3;
+	u64 unk_38;
+
 	u64 flags1;
 	u64 flags2;
 

drivers/gpu/drm/apple/parser.c

@@ -500,17 +500,16 @@ static int parse_mode(struct dcp_parse_ctx *handle,
 		return -EINVAL;
 
 	/*
-	 * HACK:
-	 * Ignore the 120 Hz mode on j314/j316 (identified by resolution).
-	 * DCP limits normal swaps to 60 Hz anyway and the 120 Hz mode might
-	 * cause choppiness with X11.
-	 * Just downscoring it and thus making the 60 Hz mode the preferred mode
-	 * seems not enough for some user space.
-	 */
+	* 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.
+	*/
 	if (vert.precise_sync_rate >> 16 == 120 &&
 	    ((horiz.active == 3024 && vert.active == 1964) ||
 	     (horiz.active == 3456 && vert.active == 2234)))
-		return -EINVAL;
+		out->vrr = true;
 
 	vert.active -= notch_height;
 	vert.sync_width += notch_height;

drivers/gpu/drm/apple/parser.h

@@ -91,6 +91,7 @@ struct dcp_display_mode {
 	struct dcp_color_mode sdr_444;
 	struct dcp_color_mode sdr;
 	struct dcp_color_mode best;
+	bool vrr;
 };
 
 struct dimension {