drm/edid: index CEA/HDMI mode tables using the VIC

Add a dummy entry to CEA/HDMI mode tables so they can be indexed
directly using the VIC, avoiding a +1/-1 dance here and there. This adds
clarity to the error checking for various functions that return the VIC
on success and zero on failure; we can now explicitly check for 0
instead of just subtracting one from an unsigned type.

Also add drm_valid_cea_vic() and drm_valid_hdmi_vic() helpers for
checking valid VICs.

v2: add drm_valid_cea_vic and drm_valid_hdmi_vic helpers (Ville)
    use { } instead of { 0 } for initializing the dummy modes

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1452252111-6439-1-git-send-email-jani.nikula@intel.comSigned-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_edid.c

@@ -637,8 +637,12 @@ static const struct minimode extra_modes[] = {
 /*
  * Probably taken from CEA-861 spec.
  * This table is converted from xorg's hw/xfree86/modes/xf86EdidModes.c.
+ *
+ * Index using the VIC.
  */
 static const struct drm_display_mode edid_cea_modes[] = {
+	/* 0 - dummy, VICs start at 1 */
+	{ },
 	/* 1 - 640x480@60Hz */
 	{ DRM_MODE("640x480", DRM_MODE_TYPE_DRIVER, 25175, 640, 656,
 		   752, 800, 0, 480, 490, 492, 525, 0,
@@ -987,9 +991,11 @@ static const struct drm_display_mode edid_cea_modes[] = {
 };
 
 /*
- * HDMI 1.4 4k modes.
+ * HDMI 1.4 4k modes. Index using the VIC.
  */
 static const struct drm_display_mode edid_4k_modes[] = {
+	/* 0 - dummy, VICs start at 1 */
+	{ },
 	/* 1 - 3840x2160@30Hz */
 	{ DRM_MODE("3840x2160", DRM_MODE_TYPE_DRIVER, 297000,
 		   3840, 4016, 4104, 4400, 0,
@@ -2548,13 +2554,13 @@ cea_mode_alternate_clock(const struct drm_display_mode *cea_mode)
 static u8 drm_match_cea_mode_clock_tolerance(const struct drm_display_mode *to_match,
 					     unsigned int clock_tolerance)
 {
-	u8 mode;
+	u8 vic;
 
 	if (!to_match->clock)
 		return 0;
 
-	for (mode = 0; mode < ARRAY_SIZE(edid_cea_modes); mode++) {
-		const struct drm_display_mode *cea_mode = &edid_cea_modes[mode];
+	for (vic = 1; vic < ARRAY_SIZE(edid_cea_modes); vic++) {
+		const struct drm_display_mode *cea_mode = &edid_cea_modes[vic];
 		unsigned int clock1, clock2;
 
 		/* Check both 60Hz and 59.94Hz */
@@ -2566,7 +2572,7 @@ static u8 drm_match_cea_mode_clock_tolerance(const struct drm_display_mode *to_m
 			continue;
 
 		if (drm_mode_equal_no_clocks(to_match, cea_mode))
-			return mode + 1;
+			return vic;
 	}
 
 	return 0;
@@ -2581,13 +2587,13 @@ static u8 drm_match_cea_mode_clock_tolerance(const struct drm_display_mode *to_m
  */
 u8 drm_match_cea_mode(const struct drm_display_mode *to_match)
 {
-	u8 mode;
+	u8 vic;
 
 	if (!to_match->clock)
 		return 0;
 
-	for (mode = 0; mode < ARRAY_SIZE(edid_cea_modes); mode++) {
-		const struct drm_display_mode *cea_mode = &edid_cea_modes[mode];
+	for (vic = 1; vic < ARRAY_SIZE(edid_cea_modes); vic++) {
+		const struct drm_display_mode *cea_mode = &edid_cea_modes[vic];
 		unsigned int clock1, clock2;
 
 		/* Check both 60Hz and 59.94Hz */
@@ -2597,12 +2603,17 @@ u8 drm_match_cea_mode(const struct drm_display_mode *to_match)
 		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 mode + 1;
+			return vic;
 	}
 	return 0;
 }
 EXPORT_SYMBOL(drm_match_cea_mode);
 
+static bool drm_valid_cea_vic(u8 vic)
+{
+	return vic > 0 && vic < ARRAY_SIZE(edid_cea_modes);
+}
+
 /**
  * drm_get_cea_aspect_ratio - get the picture aspect ratio corresponding to
  * the input VIC from the CEA mode list
@@ -2612,10 +2623,7 @@ EXPORT_SYMBOL(drm_match_cea_mode);
  */
 enum hdmi_picture_aspect drm_get_cea_aspect_ratio(const u8 video_code)
 {
-	/* return picture aspect ratio for video_code - 1 to access the
-	 * right array element
-	*/
-	return edid_cea_modes[video_code-1].picture_aspect_ratio;
+	return edid_cea_modes[video_code].picture_aspect_ratio;
 }
 EXPORT_SYMBOL(drm_get_cea_aspect_ratio);
 
@@ -2639,13 +2647,13 @@ hdmi_mode_alternate_clock(const struct drm_display_mode *hdmi_mode)
 static u8 drm_match_hdmi_mode_clock_tolerance(const struct drm_display_mode *to_match,
 					      unsigned int clock_tolerance)
 {
-	u8 mode;
+	u8 vic;
 
 	if (!to_match->clock)
 		return 0;
 
-	for (mode = 0; mode < ARRAY_SIZE(edid_4k_modes); mode++) {
-		const struct drm_display_mode *hdmi_mode = &edid_4k_modes[mode];
+	for (vic = 1; vic < ARRAY_SIZE(edid_4k_modes); vic++) {
+		const struct drm_display_mode *hdmi_mode = &edid_4k_modes[vic];
 		unsigned int clock1, clock2;
 
 		/* Make sure to also match alternate clocks */
@@ -2657,7 +2665,7 @@ static u8 drm_match_hdmi_mode_clock_tolerance(const struct drm_display_mode *to_
 			continue;
 
 		if (drm_mode_equal_no_clocks(to_match, hdmi_mode))
-			return mode + 1;
+			return vic;
 	}
 
 	return 0;
@@ -2673,13 +2681,13 @@ static u8 drm_match_hdmi_mode_clock_tolerance(const struct drm_display_mode *to_
  */
 static u8 drm_match_hdmi_mode(const struct drm_display_mode *to_match)
 {
-	u8 mode;
+	u8 vic;
 
 	if (!to_match->clock)
 		return 0;
 
-	for (mode = 0; mode < ARRAY_SIZE(edid_4k_modes); mode++) {
-		const struct drm_display_mode *hdmi_mode = &edid_4k_modes[mode];
+	for (vic = 1; vic < ARRAY_SIZE(edid_4k_modes); vic++) {
+		const struct drm_display_mode *hdmi_mode = &edid_4k_modes[vic];
 		unsigned int clock1, clock2;
 
 		/* Make sure to also match alternate clocks */
@@ -2689,11 +2697,16 @@ static u8 drm_match_hdmi_mode(const struct drm_display_mode *to_match)
 		if ((KHZ2PICOS(to_match->clock) == KHZ2PICOS(clock1) ||
 		     KHZ2PICOS(to_match->clock) == KHZ2PICOS(clock2)) &&
 		    drm_mode_equal_no_clocks_no_stereo(to_match, hdmi_mode))
-			return mode + 1;
+			return vic;
 	}
 	return 0;
 }
 
+static bool drm_valid_hdmi_vic(u8 vic)
+{
+	return vic > 0 && vic < ARRAY_SIZE(edid_4k_modes);
+}
+
 static int
 add_alternate_cea_modes(struct drm_connector *connector, struct edid *edid)
 {
@@ -2713,16 +2726,16 @@ add_alternate_cea_modes(struct drm_connector *connector, struct edid *edid)
 	list_for_each_entry(mode, &connector->probed_modes, head) {
 		const struct drm_display_mode *cea_mode = NULL;
 		struct drm_display_mode *newmode;
-		u8 mode_idx = drm_match_cea_mode(mode) - 1;
+		u8 vic = drm_match_cea_mode(mode);
 		unsigned int clock1, clock2;
 
-		if (mode_idx < ARRAY_SIZE(edid_cea_modes)) {
-			cea_mode = &edid_cea_modes[mode_idx];
+		if (drm_valid_cea_vic(vic)) {
+			cea_mode = &edid_cea_modes[vic];
 			clock2 = cea_mode_alternate_clock(cea_mode);
 		} else {
-			mode_idx = drm_match_hdmi_mode(mode) - 1;
-			if (mode_idx < ARRAY_SIZE(edid_4k_modes)) {
-				cea_mode = &edid_4k_modes[mode_idx];
+			vic = drm_match_hdmi_mode(mode);
+			if (drm_valid_hdmi_vic(vic)) {
+				cea_mode = &edid_4k_modes[vic];
 				clock2 = hdmi_mode_alternate_clock(cea_mode);
 			}
 		}
@@ -2773,17 +2786,17 @@ drm_display_mode_from_vic_index(struct drm_connector *connector,
 {
 	struct drm_device *dev = connector->dev;
 	struct drm_display_mode *newmode;
-	u8 cea_mode;
+	u8 vic;
 
 	if (video_db == NULL || video_index >= video_len)
 		return NULL;
 
 	/* CEA modes are numbered 1..127 */
-	cea_mode = (video_db[video_index] & 127) - 1;
-	if (cea_mode >= ARRAY_SIZE(edid_cea_modes))
+	vic = (video_db[video_index] & 127);
+	if (!drm_valid_cea_vic(vic))
 		return NULL;
 
-	newmode = drm_mode_duplicate(dev, &edid_cea_modes[cea_mode]);
+	newmode = drm_mode_duplicate(dev, &edid_cea_modes[vic]);
 	if (!newmode)
 		return NULL;
 
@@ -2878,8 +2891,7 @@ static int add_hdmi_mode(struct drm_connector *connector, u8 vic)
 	struct drm_device *dev = connector->dev;
 	struct drm_display_mode *newmode;
 
-	vic--; /* VICs start at 1 */
-	if (vic >= ARRAY_SIZE(edid_4k_modes)) {
+	if (!drm_valid_hdmi_vic(vic)) {
 		DRM_ERROR("Unknown HDMI VIC: %d\n", vic);
 		return 0;
 	}
@@ -3170,24 +3182,24 @@ static void fixup_detailed_cea_mode_clock(struct drm_display_mode *mode)
 {
 	const struct drm_display_mode *cea_mode;
 	int clock1, clock2, clock;
-	u8 mode_idx;
+	u8 vic;
 	const char *type;
 
 	/*
 	 * allow 5kHz clock difference either way to account for
 	 * the 10kHz clock resolution limit of detailed timings.
 	 */
-	mode_idx = drm_match_cea_mode_clock_tolerance(mode, 5) - 1;
-	if (mode_idx < ARRAY_SIZE(edid_cea_modes)) {
+	vic = drm_match_cea_mode_clock_tolerance(mode, 5);
+	if (drm_valid_cea_vic(vic)) {
 		type = "CEA";
-		cea_mode = &edid_cea_modes[mode_idx];
+		cea_mode = &edid_cea_modes[vic];
 		clock1 = cea_mode->clock;
 		clock2 = cea_mode_alternate_clock(cea_mode);
 	} else {
-		mode_idx = drm_match_hdmi_mode_clock_tolerance(mode, 5) - 1;
-		if (mode_idx < ARRAY_SIZE(edid_4k_modes)) {
+		vic = drm_match_hdmi_mode_clock_tolerance(mode, 5);
+		if (drm_valid_hdmi_vic(vic)) {
 			type = "HDMI";
-			cea_mode = &edid_4k_modes[mode_idx];
+			cea_mode = &edid_4k_modes[vic];
 			clock1 = cea_mode->clock;
 			clock2 = hdmi_mode_alternate_clock(cea_mode);
 		} else {
@@ -3205,7 +3217,7 @@ static void fixup_detailed_cea_mode_clock(struct drm_display_mode *mode)
 		return;
 
 	DRM_DEBUG("detailed mode matches %s VIC %d, adjusting clock %d -> %d\n",
-		  type, mode_idx + 1, mode->clock, clock);
+		  type, vic, mode->clock, clock);
 	mode->clock = clock;
 }