drm: apple: pasrser: Reject high refresh / resolution modes

DSC setup seems to require extra steps. dcp reports itself a bandwith
limit of 926484480:
`IOMFB removing mode: 3840 x 2160 @ 119, bw: 987033600 max: 926484480`

Signed-off-by: Janne Grunau <[email protected]>

Author: jannau

drivers/gpu/drm/apple/parser.c

@@ -475,6 +475,20 @@ static int parse_mode(struct dcp_parse_ctx *handle,
 	     (horiz.active == 3456 && vert.active == 2234)))
 		return -EINVAL;
 
+	/*
+	 * HACK: reject refresh modes with a pixel clock above 926484,480 kHz
+	 *       (bandwidth limit reported by dcp). This allows 4k 100Hz and
+	 *       5k 60Hz but not much beyond.
+	 *       DSC setup seems to require additional steps
+	 */
+	if (calculate_clock(&horiz, &vert) > 926484) {
+		pr_info("dcp: rejecting mode %lldx%lld@%lld.%03lld (pixel clk:%d)\n",
+			horiz.active, vert.active, vert.precise_sync_rate >> 16,
+			((1000 * vert.precise_sync_rate) >> 16) % 1000,
+			calculate_clock(&horiz, &vert));
+		return -EINVAL;
+	}
+
 	vert.active -= notch_height;
 	vert.sync_width += notch_height;