From 32958d28d4319afa69feb33a5db86ea0c5d8f3fd Mon Sep 17 00:00:00 2001
From: Sorgelig <pour.garbage@gmail.com>
Date: Wed, 29 Apr 2026 22:40:14 +0800
Subject: [PATCH] video: add VRR_MISTER mode.

---
 MiSTer.ini |  1 +
 cfg.cpp    |  4 ++--
 video.cpp  | 36 ++++++++++++++++++++++++++++--------
 3 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/MiSTer.ini b/MiSTer.ini
index 29f7e74..ff87fb4 100644
--- a/MiSTer.ini
+++ b/MiSTer.ini
@@ -331,6 +331,7 @@ bt_reset_before_pair=0
 ; 1 - Auto Detect VRR from display EDID. 
 ; 2 - Force Enable Freesync
 ; 3 - Force Enable Vesa HDMI Forum VRR
+; 4 - Force Enable MiSTer VRR
 vrr_mode=0
 ; Minimum framerate in VRR mode. 
 vrr_min_framerate=0
diff --git a/cfg.cpp b/cfg.cpp
index e327677..15f869c 100644
--- a/cfg.cpp
+++ b/cfg.cpp
@@ -104,7 +104,7 @@ static const ini_var_t ini_vars[] =
 	{ "WHEEL_FORCE", (void*)(&(cfg.wheel_force)), UINT8, 0, 100 },
 	{ "WHEEL_RANGE", (void*)(&(cfg.wheel_range)), UINT16, 0, 1000 },
 	{ "HDMI_GAME_MODE", (void *)(&(cfg.hdmi_game_mode)), UINT8, 0, 1 },
-	{ "VRR_MODE", (void *)(&(cfg.vrr_mode)), UINT8, 0, 3 },
+	{ "VRR_MODE", (void *)(&(cfg.vrr_mode)), UINT8, 0, 4 },
 	{ "VRR_MIN_FRAMERATE", (void *)(&(cfg.vrr_min_framerate)), UINT8, 0, 255 },
 	{ "VRR_MAX_FRAMERATE", (void *)(&(cfg.vrr_max_framerate)), UINT8, 0, 255 },
 	{ "VRR_VESA_FRAMERATE", (void *)(&(cfg.vrr_vesa_framerate)), UINT8, 0, 255 },
@@ -602,7 +602,7 @@ void cfg_parse()
 	cfg_error_count = 0;
 	strcpy(cfg.autofire_rates, "10,15,30");
 	strcpy(cfg.screenshot_image_format, "png");
-	
+
 	ini_parse(altcfg(), video_get_core_mode_name(1));
 	if (has_video_sections && !using_video_section)
 	{
diff --git a/video.cpp b/video.cpp
index 8892aeb..1d784ce 100644
--- a/video.cpp
+++ b/video.cpp
@@ -58,6 +58,7 @@
 #define VRR_NONE     0x00
 #define VRR_FREESYNC 0x01
 #define VRR_VESA     0x02
+#define VRR_MISTER   0x03
 
 static int     use_vrr = 0;
 static int     use_freesync_spd = 0;
@@ -90,10 +91,11 @@ struct vrr_cap_t
 	char description[128];
 };
 
-static vrr_cap_t vrr_modes[3] = {
+static vrr_cap_t vrr_modes[] = {
 	{0, 0, 0, 0, "None"},
 	{0, 0, 0, 0, "AMD Freesync"},
 	{0, 0, 0, 0, "Vesa Forum VRR"},
+	{0, 0, 0, 0, "MiSTer VRR"},
 };
 
 static uint8_t last_vrr_mode = 0xFF;
@@ -1976,7 +1978,6 @@ static void set_vrr_mode()
 {
 	PROFILE_FUNCTION();
 
-	use_vrr = 0;
 	float vrateh = 100000000;
 
 	if (cfg.vrr_mode == 0)
@@ -1988,6 +1989,7 @@ static void set_vrr_mode()
 		}
 		last_vrr_mode = 0;
 		use_freesync_spd = 0;
+		use_vrr = 0;
 		return;
 	}
 
@@ -1996,16 +1998,17 @@ static void set_vrr_mode()
 
 	if ((last_vrr_mode == cfg.vrr_mode) &&
 		(last_vrr_rate == vrateh) &&
-		(last_vrr_vfp == v_cur.param.vfp || cfg.vrr_mode != VRR_VESA)) return;
+		(last_vrr_vfp == v_cur.param.vfp || (cfg.vrr_mode != VRR_VESA && cfg.vrr_mode != VRR_MISTER))) return;
 
 	if (!is_edid_valid())
 	{
 		get_active_edid();
 	}
 
-	if (!is_edid_valid())
+	if (!is_edid_valid() && cfg.vrr_mode == 1)
 	{
 		printf("Set VRR: No valid edid, cannot set\n");
+		use_vrr = 0;
 		return;
 	}
 
@@ -2030,6 +2033,10 @@ static void set_vrr_mode()
 	{ //force Vesa Forum VRR
 		use_vrr = VRR_VESA;
 	}
+	else if (cfg.vrr_mode == 4)
+	{ //force MiSTer VRR
+		use_vrr = VRR_MISTER;
+	}
 	else
 	{
 		use_vrr = 0;
@@ -2041,8 +2048,11 @@ static void set_vrr_mode()
 	if (use_vrr == VRR_VESA && !vrateh) return;
 	if (use_vrr)
 	{
-		vrr_min_fr = cfg.vrr_min_framerate;
-		vrr_max_fr = cfg.vrr_max_framerate;
+		if (use_vrr != VRR_MISTER)
+		{
+			vrr_min_fr = cfg.vrr_min_framerate;
+			vrr_max_fr = cfg.vrr_max_framerate;
+		}
 
 		if (!vrr_min_fr) vrr_min_fr = vrr_modes[use_vrr].min_fr;
 		if (!vrr_max_fr) vrr_max_fr = vrr_modes[use_vrr].max_fr;
@@ -2132,7 +2142,7 @@ static void video_set_mode(vmode_custom_t *v, double Fpix)
 	}
 
 	if (Fpix) setPLL(Fpix, &v_cur);
-	if (use_vrr)
+	if (use_vrr && vrr_min_fr && vrr_max_fr)
 	{
 		printf("Requested variable refresh rate: min=%dHz, max=%dHz\n", vrr_min_fr, vrr_max_fr);
 		int horz = v_fix.param.hact + v_fix.param.hbp + v_fix.param.hfp + v_fix.param.hs;
@@ -2626,7 +2636,6 @@ static bool get_video_info(bool force, VideoInfo *video_info)
 	uint16_t res = spi_w(0);
 	if ((nres != res) || force)
 	{
-
 		res_changed = (nres != res);
 		nres = res;
 		if (res_changed) vi_seen = true;
@@ -3130,6 +3139,17 @@ void video_mode_adjust()
 			user_io_send_buttons(1);
 			force = true;
 		}
+		else if (use_vrr == VRR_MISTER)
+		{
+			int fr = 1000000000 / video_info.vtime;
+			int fr_min = (fr - 10) / 10;
+			int fr_max = (fr + 19) / 10;
+			vrr_modes[VRR_MISTER].min_fr = fr_min;
+			vrr_modes[VRR_MISTER].max_fr = fr_max;
+			video_set_mode(&v_def, 0);
+			user_io_send_buttons(1);
+			force = true;
+		}
 		else if (cfg_has_video_sections()) // if we have video sections but aren't updating the resolution for other reasons, then do it here
 		{
 			video_set_mode(&v_def, 0);