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 <[email protected]>

Author: chadmed

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 */