1 files changed, 54 insertions, 12 deletions

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 7eec18925b70..728990fee4ef 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2613,6 +2613,41 @@ cea_mode_alternate_clock(const struct drm_display_mode *cea_mode)
 	return clock;
 }
 
+static bool
+cea_mode_alternate_timings(u8 vic, struct drm_display_mode *mode)
+{
+	/*
+	 * For certain VICs the spec allows the vertical
+	 * front porch to vary by one or two lines.
+	 *
+	 * cea_modes[] stores the variant with the shortest
+	 * vertical front porch. We can adjust the mode to
+	 * get the other variants by simply increasing the
+	 * vertical front porch length.
+	 */
+	BUILD_BUG_ON(edid_cea_modes[8].vtotal != 262 ||
+		     edid_cea_modes[9].vtotal != 262 ||
+		     edid_cea_modes[12].vtotal != 262 ||
+		     edid_cea_modes[13].vtotal != 262 ||
+		     edid_cea_modes[23].vtotal != 312 ||
+		     edid_cea_modes[24].vtotal != 312 ||
+		     edid_cea_modes[27].vtotal != 312 ||
+		     edid_cea_modes[28].vtotal != 312);
+
+	if (((vic == 8 || vic == 9 ||
+	      vic == 12 || vic == 13) && mode->vtotal < 263) ||
+	    ((vic == 23 || vic == 24 ||
+	      vic == 27 || vic == 28) && mode->vtotal < 314)) {
+		mode->vsync_start++;
+		mode->vsync_end++;
+		mode->vtotal++;
+
+		return true;
+	}
+
+	return false;
+}
+
 static u8 drm_match_cea_mode_clock_tolerance(const struct drm_display_mode *to_match,
 					     unsigned int clock_tolerance)
 {
@@ -2622,19 +2657,21 @@ static u8 drm_match_cea_mode_clock_tolerance(const struct drm_display_mode *to_m
 		return 0;
 
 	for (vic = 1; vic < ARRAY_SIZE(edid_cea_modes); vic++) {
-		const struct drm_display_mode *cea_mode = &edid_cea_modes[vic];
+		struct drm_display_mode cea_mode = edid_cea_modes[vic];
 		unsigned int clock1, clock2;
 
 		/* Check both 60Hz and 59.94Hz */
-		clock1 = cea_mode->clock;
-		clock2 = cea_mode_alternate_clock(cea_mode);
+		clock1 = cea_mode.clock;
+		clock2 = cea_mode_alternate_clock(&cea_mode);
 
 		if (abs(to_match->clock - clock1) > clock_tolerance &&
 		    abs(to_match->clock - clock2) > clock_tolerance)
 			continue;
 
-		if (drm_mode_equal_no_clocks(to_match, cea_mode))
-			return vic;
+		do {
+			if (drm_mode_equal_no_clocks_no_stereo(to_match, &cea_mode))
+				return vic;
+		} while (cea_mode_alternate_timings(vic, &cea_mode));
 	}
 
 	return 0;
@@ -2655,18 +2692,23 @@ u8 drm_match_cea_mode(const struct drm_display_mode *to_match)
 		return 0;
 
 	for (vic = 1; vic < ARRAY_SIZE(edid_cea_modes); vic++) {
-		const struct drm_display_mode *cea_mode = &edid_cea_modes[vic];
+		struct drm_display_mode cea_mode = edid_cea_modes[vic];
 		unsigned int clock1, clock2;
 
 		/* Check both 60Hz and 59.94Hz */
-		clock1 = cea_mode->clock;
-		clock2 = cea_mode_alternate_clock(cea_mode);
+		clock1 = cea_mode.clock;
+		clock2 = cea_mode_alternate_clock(&cea_mode);
 
-		if ((KHZ2PICOS(to_match->clock) == KHZ2PICOS(clock1) ||
-		     KHZ2PICOS(to_match->clock) == KHZ2PICOS(clock2)) &&
-		    drm_mode_equal_no_clocks_no_stereo(to_match, cea_mode))
-			return vic;
+		if (KHZ2PICOS(to_match->clock) != KHZ2PICOS(clock1) &&
+		    KHZ2PICOS(to_match->clock) != KHZ2PICOS(clock2))
+			continue;
+
+		do {
+			if (drm_mode_equal_no_clocks_no_stereo(to_match, &cea_mode))
+				return vic;
+		} while (cea_mode_alternate_timings(vic, &cea_mode));
 	}
+
 	return 0;
 }
 EXPORT_SYMBOL(drm_match_cea_mode);